Thai massage happy ending they usually use some wet small towel to clean my penis i hope they change it but what if there is some semen left from under customer this my worries any std risk? no other thing only handjob?

Risks: I would expect strict infection control standards where massage therapists are working. However, I think when dealing with sex workers, sanitation may be questionable. Although there is likely limited risk if potentially contaminated fabric is used, can't say no risk. Scabies ,pubic lice & molluscum contagiosum may be spread via cloth.