I work in the PCB (printed circuit board) manufacturing industry as an electrical engineer. Now that could mean nothing, but I deal with hardware like this on a daily basis and my humble opinion is that if the contacts ever get dirty (I'm not really sure why, but whatever.) then there would be nothing wrong with taking a Q-tip with some alcohol on it to clean the contacts. Wipe it dry or let it air dry, obviously, before plugging it in. Alcohol isn't conductive, but I just wouldn't dunk a module in any liquid and then stick it in my amp.
The modules/connectors on the backplane of the MOD50 fit very snugly together and I'm willing to bet that the rating of that connector is probably higher than 10,000 connects/disconnects. In short, I don't see you outliving those connectors assuming you don't abuse the amp. Also, to any engineer, this would be an initial design concern and I am more than confident that Bruce took this into consideration very early in the design process. Consumer products have to be made "idiot proof" and you have to consider the worst abuse possible when designing something. Just ask Jeff how he breaks MOD50s in.