Kuros said:
Don’t forget about speed problems. For instance, “Wow that soldier is running as fast as…well…as fast as A SPY ZOMG SHOOT HIM!.” A spy’s speed is more closely matched with an engineers or a pyros. That’s something a lot of spies don’t take into consideration.
Someone who plays spy more than I correct me if I”m wrong. But I believe when the spy disguises his speed is matched to the disguise.