When it comes to ugly chicks alot of guys will try to hit on them because they think those girls are easier but they arent for these reasons

1) Hotness is fairly relative a girl you might think is ugly might be attractive to another guy. Who would she rather go for, a guy whos hitting on her thinking that she is easy because she is ugly or a guy whos generally into her. (girls can pick up these behaviors really easily.)

2) Girls put alot of effort into their appearance, chances are if a girl is ugly she might not one of "those girls" who is obsessed with being hot and will actually be harder to hook up with simply because she looks for more deeper qualities. Those are typically nerdy/shy girls who also want a guy they can relate to.

3) She may come from another culture where there are different beuty standards(traditional indian girl or conservative church girl) who is not interested in random hookups. Or she could be from a subculture eg goth, hippie etc or some fetish scene and is not into maintream hookup culture.

4) Ugly chicks have some of the strongest bitch shields rejecting any guy that talks to them.

5) They are girls too and have the same high standards