I was there last summer but I had already company so wasn't looking for brothels or sex clubs. Nor did i spot any street hookers anywhere.
But i saw one strip club on the corner of the main square, they had high class looking girls outside trying to lure gentlemen in and it didn't look too shady so it might be legit. Also considering the location it might be so. But you never know, do your background check before getting in is my advice, as always.
Lviv is very touristy place, maybe more than any other Ukrainian city I've been to so that might be a good or it might be a bad thing considering about punting. But the bars are busy most of the days and you can go on until the morning, there'll always be some place open somewhere.
Wish you all the best and hope you're doing great over there!