I was once bitten on the backside by a brown recluse. Sitting on a woodpile is not something that I will ever do again. In my case I was fortunate and the envenomation wasn't that heavy so I didn't get the out of control infection that usually results from these bites. However, it took a good 8 weeks for the sore to heal. What is really nasty about the brown recluse is that the bite is painless, you don't know you've been bitten until the bite erupts.
Now, if I see a spider, I kill it, even if I have to spend time stalking it. They way I look at it, I'm just trying to get even. I figure if I live for another 50 years I may even up the score. Which means I'll be hunting spiders until I am older that George Burns.