I know adsense is not allowed on sites with adult content/images, but what constitutes adult content? For example, is site with photos of a girl in a bikini, or something skimpy against the TOS?
Yes if bikni is too short than it may be considered as adult content too , we have seen many cases where children and their moms report some short bikni hot girls in adult content and account get banned . you have seen micro bikini they are adult .