Yup. Geeks (male and female) can be dense about flirting at times, though. I'd like to think that I'm more perceptive nowadays, but when I was a sophomore in college I was asked out and taken on a date without realizing it, for instance. So be aware that they might just be really enjoying the conversation and not realizing that you're trying to flirt. Which doesn't even mean they wouldn't be happy to flirt back if they realized how things were! So again, just always be willing to revise your assumptions about the situation, and always be polite and be ready to back out if you misread things.