Hotmail and AOL Spam Reports

Edit Subject

I've noticed that all of the spam complaints on my account are from Hotmail/Live/MSN or AOL/AIM.

The percentage of spam reports is low, but I'd still like to improve it if possible. I suspect the reports might be automated based on the fact that they only come from those two providers. Is there anything unusual about those providers that might explain the frequency of spam reports? Is there anything I can change about my messages to minimize the spam reports?