I've been very busy the last few days - painting frames and ugly mats which had a hideous color on them. Yes, you can paint mats. Just do it "drily" and don't get the mats too wet. I wouldn't do it if I was going to sell it but for my own use I would. Nuuuuuu, don't do it to a picture with value to it because it would probably devalue, it but to one that isn't much more than eye candy for you, it would be fine.
Here's the remodel we hope to get done this summer. I'm dreading the plaster dust all over the house but it gives me more wall space and I definitely need that, my sweet chicks!! :-)