Imagine the rowdiest local pub you know, where 99% of the customers are absolutely smashed, embarrassing drunken behaviour is condoned and the crowd dances and stamps on the tables to awful, awful music played at full blast. Then imagine the landlord of this debauched venue deciding to convert the upstairs into a hotel. Not a flophouse for passed-out pissheads. A stylish boutique hotel. With a fancy spa. Sounds a bad idea, doesn't it?

And yet here I am, paddling out into a sleek turquoise infinity pool. Fat snowflakes drop onto my wet hair as I swim slowly through steam towards pine trees, and there is not a sound except the gurgles from a stream in the gorge below.

It is perfectly peaceful. Heavenly. So much so it's hard to believe that just around the corner throngs of beered-up Germans are swigging steins of weissbier, knocking back Jägermeisters and singing along to "heeyyyyyy, hey-ey ba-by... ooh! ah!..." played from mammoth speakers.

For on the other side of the building to my gorgeous spa, so cool with its exposed brick walls, designer chairs and colourful pouffes that it ought to be a nightclub, is the Mooserwirt.

Anyone who has skied St Anton's world-class slopes knows the Mooserwirt. It is an infamous institution of intoxication. A sprawling multi-levelled place with a huge outdoor terrace, where more beer is served (per square metre anyway) than in almost any other bar in Austria, and 37km of plastic tubing feeds booze up to the busy bar, where there is space for 2,000 beer-swilling customers – a largely German-speaking contingent who chant the lyrics to Euro-pop après ski anthems ("Hey! Wir woll'n die Eisbären seh'n! O ho ho ho hoh!") and stomp in their ski boots.

It appears in every list of the world's best après ski bars – along with its neighbour the Krazy Kanguruh, which has a policy of giving free champagne to girls who take their tops off to dance. And probably nowhere in the world is chucking-out time so dangerous. Forget 2am outside Newcastle's roughest pubs: when the bell rings at these two bars, some 500 beered-up people put on their skis and stampede in the dark from the top of the final run to the resort village.

But now there is an alternative to this perilous descent. After five decades of trading in hangovers on what was once his family's farm, owner Eugen Scalet has extended his family flat above the raucous bar and turned it into the boutique Mooser hotel.

If you're a guest here, you simply take your woozy head round the back of the building to where sliding glass doors lit with sparkling lights lead to a lobby whose designer tables are decorated with artistic bowls of fruit and wreaths of winter flowers, stagger up into your gorgeous suite and pass out on a high-spec bed heaped with expensive bedding.

When St Anton's newest mountain sanctuary opened in early December, the question in every potential guest's mind was, would you be able to hear the music? The answer is no. Even out on my decked balcony, where I slump on a Fat Boy (a posh beanbag) covered in a sheepskin rug and sip a beer from the complimentary mini bar, I strain to hear the beat, and inside with the doors shut it is completely inaudible.

This is certainly no party hotel. Interestingly, Eugen says that 90% of bookings so far are from people who have never drunk in the Mooserwirt. The Mooser is hip in a refined way, with nine suites and eight double rooms. There is Italian designer furniture from Moroso, lighting from Foscarini, leather sofas, Bose stereos, and a Zirben Klimabox to naturally purify and scent the air. Electronics control the blinds on the balcony and the bathroom, which is in a glass cube at one end of the room (the loo is separate). It is all very well thought-out and stylishly executed.

My only gripe – and it's a pathetic one – is that it's a bit too comfy: too warm, the bed too padded and soft. But it is classy. Very. Yet the same building is hosting performances by peroxide-haired Hamburg dance act Scooter, and by DJ Ötzi himself (of Hey Baby fame).

They and other Germanic Euro-pop royalty are in town the weekend I'm there, performing live at the Mooserwirt for German channel RTL, which has filmed a show in the bar every December for the past 11 years, taking it over for the weekend with a sort of extremely well-lit mini festival.

Although it is thrilling to see live lip-synching and know that silver-catsuited dance troupes are, in Austria at least, still alive and high-kicking, I think I'd rather have witnessed the usual Mooserwirt shenanigans. (The regular DJ, Gerhard, has been there since 1994. He is now 62 and still plays seven days a week.) But then I surprise myself by feeling more drawn to the spa and the guests-only hotel bar, with its view down blue-white slopes to the twinkling lights of the resort, than to noisy crowds and pre-mixed spirits on tap. Maybe it is not just the Mooserwirt that is growing up.

At 8pm, when the mountain bars close, we hotel guests can take a cosy seat in the superior Mooser bar, beside a panoramic window, watch the mayhem spill out from the Mooserwirt down the mountain, then be left in peace to enjoy starry skies and a beautiful meal. (If you want a bit more life, it's a €10 cab ride into town.)

The Mooser's bar and restaurant are not open to the public, so no one staggers in half-cut to request a kebab. We enjoy delicious dishes such as silky pumpkin soup, ox carpaccio, smoked Arctic char, perfect wiener schnitzel and tender tender steak. Next morning brings a great breakfast of bircher muesli, meat, cheese, fruit and extras such as omelettes and beef tartare with toast. But the real bonus is that you're already at the top of the slopes, ready to clip into your skis and, before the lifts even open, hit the hill and begin exploring this fantastic ski resort.

The hotel is fabulous (it should be: it cost €12m) but it is not without competition. There is a glut of stylish high-end, hi-tech new hotels in St Anton but, wonderfully, they are all owned by local families, who have expanded existing businesses. The new 26-room M3 hotel, though rather more bland than the Mooser, is owned by the three brothers who run the Hacienda restaurant beneath it, widely considered the town's finest.

High design and sophistication is part of a trend in St Anton. Even the Krazy Kanguruh has changed. Under new owner Mario Matt, a professional skier, it has been poshed up (for the worse, I fear) with expensive lighting and shiny fittings, while its old owner, Swede Gunnar Munthe, has gone off to launch his own hotel, the Reselehof.

On the main drag, a new bar, the Murrmel, looks like a sleeker offering than the popular Piccadilly and Scotty's, while the favourite bar of Scandinavian skiers, the Funky Chicken, has been replaced by Anthony's, which includes a pizza place and a steak house, with another boutique hotel – Life & Style, complete with rooftop Jacuzzi – opening upstairs next winter.

No one wants St Anton to lose its reputation as a fun resort, but the mayor is trying to put the stoppers on the growing problem of noisy drunks taking over the streets when they come down from the mountain, a problem worsened by the smoking ban. Locals are sick of the racket, and indeed of the sick, of which there is lots, apparently, and the mayor is pushing bars in town to ban ski boots, so people are forced to go home and change – and sleep.

Of course guests of the Mooser need not worry themselves about such tawdry issues: in the steam of the spa they can immerse themselves in this stylish, grown-up version of one of the world's most famous party resorts.

• Kaluma Ski (01730 260263, kalumatravel.co.uk) is currently the only UK tour operator to offer the Mooser hotel, with seven nights' half-board including BA flights from Gatwick, transfers and the Kaluma concierge service, for £1,260. Kaluma also offers stays at the M3 and, from next season, Anthony's Life & Style Hotel. For resort information see stantonamarlberg.com and tyrol.com