I love reading your posts theleip, you have a way of saying the things I kind of know but would struggle to put into words.
For me, the 'cheat' meal is largely a psychological thing. Its my reward for working hard all week and sticking to my training/diet regime. I don't necessarily go mad but, I definitly treat myself. I realise that, sometimes, this may slow down my progress but, that doesn't bother me as long as I am still making reasonable progress.
It may not be for everyone but, it works well for me.