I don't keep my tags in my regular inbox, but in separate folders (one for each of my games), so it's not too bad for me until I'm hitting 50+ tags in one folder. I rarely ever get more than 50 tags ever (and I cheated and put my prom tags in a folder of their own to keep the numbers down).
So yeah, around 50+ tags is stressful for me at one time, but I usually get daunted when I'm going through the tags and I'm getting 2 tagbacks for every tag I complete. Then I start hearing "These are the tags that never end~" in my head. /headdesk