Covert and Undercover

Is it wrong to use a..hmm...system of covertness/undercover to find out stuff on someone who owes you money when you have a signed contract.

Basically an ass I sold my old PS2 too has signed a contract stating I am owed more money for it, but I haven't been paid. Is it wrong to use an undercover alias to find out like where they work and all the details of their lives then to skillfully use it to your advantage?

And in that, how would you use said information to your advantage.

Think of it this way, if he owes you $20 and he's an ass that you never want to talk to again, then you just spent $20 so you never have to deal with him again.