Totally, the weight is a dead giveaway for me too. I had a fake roman denarius that just felt weirdly light in the hand. Now I always check the edges first, the wear patterns on real coins just look different.
@garcia.sean, you said your fake denarius felt light? That's wild because I always thought fakes would be heavier to seem real. Maybe it's just me but now I'm gonna be paranoid about weight too.