I used to google girls before dates, but there was one who had done some fascinating stuff in her life, and it sucked having to decide between letting her know that I'd googled her and pretending to be surprised when she told me the stories, so I stopped doing that for a while.
After that, I went through a period where I wouldn't do any internet searching about girls before dates. That seemed to work well until I went to add a girl on Facebook after a few, um, "successful" dates and saw Relationship Status: Married.
Checking the Facebook relationship status to clear my conscience but otherwise not doing any searching is the compromise I've settled on for now.