Tape yourself shirtless. I did once, back when my body fat was higher than it is now, and I actually looked better than I thought I did. May've been the light though, LOL.
I've seen some pics where Cro Cop and Diego don't look very defined, while other times you can see clear six-packs on them.
It's virtually impossible to look defined in all lights. What I'm striving for is to have NO visible body fat in any light. That way, even if I'm in a bad light I still have the correct "shape."