For overrated... Riley Reid for sure. Not only that but the thing she admitted of doing... oof. Gtfo. (Also I don't find her attractive at all but, subjective)
For plain ugly... as you guys already said : Mia Khalifa, Asa Akira, Lucie Wilde (never cared for her but why not, I do agree with you), Lisa Ann, Dillion Harper, Ava Addams, Madison Ivy and Aletta Ocean to quote the most famous ones.
I really don't see what people see in them.
(I don't mean to offend anyone, it's just my opinion and everyone's opinion is different!)