Russian to English Art/Literary Poetry & Literature

Although this could mean simply smiling in enjoyment, it seems to me something more sinister is being suggested...no? But translating "Bared their teeth merrily" is perhaps a little too strong and too threatening.

In this story a 10-year old is apprenticed to a barber shop in the city, which is depicted as decadent, oppressive, and colorless, then later goes to the dacha which is depicted the opposite.

Any thoughts or suggestions welcome!

Случалось, пьяный мужчина бил такую же пьяную женщину; она падала, поднималась и снова падала; но никто не вступался за нее. Зубы весело скалились, лица становились осмысленнее и живее, около дерущихся собиралась толпа; но когда приближался ярко-синий сторож, все лениво разбредались по своим местам.