What are some good and bad puns?

These ones in my opinion are bad:

*She criticized my apartment, so I knocked her flat.
*I have actually asked photographers to step into the darkroom with me so we could see what develops
*Someday I hope I'll be asked to introduce an archeologist. I'll refer to him as one whose carrer lies in ruins.
*I'm waiting to run into someone who'll remind me that in the Middle Ages people with the plague were required to wear bells around their necks to warn others of their disease. "Ring around the choler," I'll holler-and run for my life.

How would I justify these choices? Thank You in advance

Actually, I like these puns.

What do you think is the difference between good and bad puns? It seems to me that it's all a matter of taste.

While we're on puns, check out these puns.

(Broken Link Removed)