I agree with several of the posters here. If the number 1 reason for not participating is due to broken exchanges, and you want to improve the process, you need to look at a proactive process similar to what David describes. Although that process increases the amount of work the exchange coordinator must perform, it guarantees that nobody receives a print if they didn't send a print. If increasing participation via eliminating broken exchanges is truely paramount, the extra work should be inconsequential.
If you are looking to simply limit the damage without revamping the process, then it certainly makes sense to prevent people who have a history of creating broken exchanges to continue to participate in print exchanges. I don't think this should be a universal rule however. If the exchange coordinator chooses to look at the black list and limit participation it should be up to them. I would imagine that the coordinator should post the participation rules that the specific exchange is using so that people can choose to participate or not based on what they feel their risk might be.


John