Why does it feel like you've parked just fine, straight, and even in your parking space but when you step out and look you're all crooked in there?

It’s the other way round for me, I think I park crooked and out of the parking zone and then I get out and find I parked okay. But then again I think I park close enough to the curb at side of road and then I get out and realise I’m parked nearly in the middle of the road. I know what you mean.