She says her dates have got it wrong by being too effeminate, sending too many text messages, and trying to over impress.
The 30-year-old singer, who was recently linked with Limp Bizkit's Fred Durst, made the revelation in her new autobiography Just For The Record.
"The first one was a bit uptight - too effeminate, possibly gay," she says in the book.
"With the second I put a note through his door but got no reply! The third was a lapdog - he wanted to move in after our first date.
"The fourth was a serial texter and couldn't get beyond that.
"Number five was trying to overly impress, telling me his bank balance and offering me career advice. I quite liked number six but wasn't sure what we had in common.
"And as for my "lucky" number seven, life just pushed us apart."
