Hi!
I am part of the McMaster Residence Green Team. We started up back in 2011 and our main goal that initial year was to improve how students recycle. We found out that when a recycling bin is contaminated, sometimes it has to be thrown into the trash instead. We changed the posters (THIS/THAT/OTHER) above the different bins in residence dramatically that year. If you notice the ones that are up now, they are very clear. The most pressing problem is motivating students to follow the guidelines properly.
Also, you are correct that residence recycling is not with the City of Hamilton but with Waste Management Inc (which means the recycling guidelines are slightly different).
If you want to chat, please send us a PM!