ALTDave sort has this all covered.
I started shooting USPSA in 2005 and since that start I have busted 3 or 4 base pads dropping magazines on concrete. That was a quick and easy fix, if slightly costly. I have had a couple mag bodies dented or bent by being dropped or step on by myself, RO's or squad-mates resetting stages. Most of the time it was non-issue and in the few it wasn't a few minutes with a piece of bar stock in my bench vice and a dead blow hammer and the dents got ironed out.
Magazine are going to get dirty if you drop them. Come prepared to clean them. I have a brush and a rag and rod in my range bag for just that reason. I have shot matches that were so wet and muddy that we would assign one or two people to watch where competitor's dropped magazines because mud puddles would swallow them up and they would not be easy to find. I have had to wash the bulk of the mud out of magazines in standing water puddles in a few really bad cases.
The advantage of moonclips shoot'em, let em drop in the mud, and clean them at home.
Speed-loaders are the worst though cause once you get mud into the inter-workings of the release its a pain to get them clean at a match as they don't come apart easily like a magazine does.
And come to think of it I am pretty sure I have broken or witness another competitor break just about every picece of kit commonly worn at a USPSA or IPDA match at one time or another. Holster break, mag pouches fail, gun break, etc, etc, etc. If you run it hard your very likely going to eventually break it. Better to break it in competition, practice, or training then on the streets I guess...