We have a book system as mentioned in the thread Geoff cites above. We do get the usual excuses - "It's not my job" or "I never left it like that" or even "It looks clean enough to me". I dread to think that we have enough trouble getting the stuff clean to service it - what state is it in when used on patients?

I have used the system to return filthy equipment, and demand that items are cleaned properly. It tends to get me a reputation as Miss Whiplash, but it does pay off over time if you stick to your guns.

I don't let petty behaviour get me down, and smile sweetly as if I really am grateful that they deigned to do what they should have done in the first place!
I have called the infection control nurses, who backed me up when equipment was being repeatedly sent in filthy. Eventually, the message sinks in.
I don't mind internal equipment contamination as long as I have prior warning and some PPE to hand. I have stripped two Graseby 500 pumps down in the sink in the past year when bags of blood have been spilled into them. They are recoverable, though I do hate to see those precious blood donations wasted.
We also have an Equipment Trainer/Training Co-ordinator - something someone asked about on one of these two related threads. She was a nurse for years, but now she has joined our Medical Physics department to train users and co-ordinate outside training. If we identify a ward where there are any training issues, contamination or user-related, she will go and sort things out with the senior nursing staff. Every department should have someone like her!
Our equipment library is about to spread to our sister hospital, and is a 24 hour system for essentials (e.g. defib pads, suction, infusion pumps, nebuliser compressors). It does help to reduce the amount of dirty and broken equipment around the place, and cuts the overall amount of equipment needed.