I remember one time many years ago I was fishing a muddler against a big rock cliff. I had to make some pretty huge casts, and smacked the fly on the rocks behind me a couple times. Anyhow, some very large, very hungry trout were in the mood for minnows that day, and I must have had dozens of giant hits over the course of a couple hours. These fish were big, and I couldn't set the hook to save my life. I was frustrated almost to the point of tears.

Eventually I'd spooked them all down and reeled my line in to head for the next hole. On inspection of my fly, I noticed a little something that might have been making it hard to keep a fish on the line - I had no darn hook! I'd completely broken the tip off on one of my brilliant back-smacking casts.

Since then I'm always paranoid about hook condition when I start missing fish - ESPECIALLY when I'm getting hits with multiple jerks where the fish clearly had the fly in its mouth and wasn't just spitting it out. Keep em sharp and don't let em rust...and, um, don't break them off.