There's a big difference between the 1100 who says this and loses to 1200's, and the 1100 who says this because he had to forfeit 100 concurrent online games when he went into the hospital for a month.
Sometimes, it's true. Sometimes, it's not. All the time, who cares? You're as good as the moves you make on the board.
Does anyone else ever hear other players say this? I know a guy who is 1100 who consistently and convincingly loses to a guy who is almost 1300 and kids who are 1200... yet somehow thinks he's better than his rating! I'm sorry, but if you play like an 1100 and obtain 1100 results, then you are an 1100.
I'd love to believe that I'm at least expert strength, but the thing is if I were I wouldn't have a big minus score against people over 2000 with only a handful of wins and draws here and there.
The first step in chess improvement is self-honesty.