I bought a flat yesterday. The final stages involved going to a bank and signing about 50 pieces of paper, then signing more with the realtor who also had to arrive at the same time.
I couldn't help noticing that my signatures were very very different on the first few papers I signed compared to the last few.
I think I was suffering from signature fatigue, but despite everybody exchanging passports and IDs, I wonder if I could come back later and "prove" the signatures on some of the papers were not my own - after all they look so different..