What is the situation like regarding sex tourism in Ukraine?

wheres demand, theres gonna be supply too. theres nothing wrong with adults exchanging goods and services by mutual concent

tho my opinion doesnt reflect the rest of society and the laws, so this is grey zone in ukraine. noone likes it, but its usually part of shady businesses aimed at foreigners, which includes the police and local officials in the money flow

Are Turks known to women in these cities?

well, to some women certainly. but this stuff is mostly confined in nightclubs etc, so not much exposure to a layman

but then therere stereotypes of course

Perhaps some other nationalities that, as an urban stereotype, prey on women?

since soviet times its been men from caucasus who also have similar stereotypes