Lion dance troupes are not gangs. The traditional ones are registered as exercise clubs (tiyushe), not as martial art schools, since the term martial art school (wuguan) would be looked upon suspiciously by the authorities in the 1950s and 60s. Members are disciplined not to look for fights outside. There's a whole artful sequence in a real lion dance, from drumming, teasing and waking the lion to plucking the prize. But I agree, the usual CNY roving troupes are just there to make noise for red packets without any proper sequence since there's limited time. They usually move around HDB flats, hawker stalls, shops and landed estates. They'll also ask for permission at the doorstep first. If you don't like it, you can just tell them no and they'll move on to the next. They can't enter condominiums unless the managements allow.