Etiquette for Rescuing Plants?

I was in Lowes last weekend and saw someone cleaning up the outside gardens. They were throwing anything that looked dead into a big trash bin. I know some of the plants were perennials that would start growing again in the spring (hostas, mums, etc...). Unfortunately, I was too chicken to ask "If you are going to throw those away, could I look through and rescue any plants that I think I can save?"

What is the proper etiquette for this? I'm sure some of you have experience! I am not terribly bold, so I could use your advice.

I did stop at Oakland Nursery this weekend, and I picked up mums in 1 gallon pots for $1.00/mum. I did this several years ago in the late autumn, and most of the mums came back the next spring. I was very pleased with that bargain; now I just have to find time to plant them!