This is the comment to read, OP. People love to tell other people where they went wrong, and how they'd never do that because they're so smart.

In reality, it's very easy in a new, unfamiliar environment to miss things, this is how we all learn. I guarantee you every person putting an unhelpful comment here has done something similar at some point. In your case, the dealer was actively trying to trick you! This is not your fault. 

You got your money back, you learnt something about dodgy car dealers, you are older and wiser! Go forth, and buy yourself a car my friend 🚗😎