Spam doesn't taste good, no matter it's source. And if their spamvertizing a site; doesn't exactly make me want to visit :lol:
As to a female only guild? Don't see much future; in part as many people who create female chars, including Nelfs and Belfs are really guys. Most of the people who I've known who are female players (as indicative by their voices on vent); tend to create male chars, and would rather not draw attention to their gender. Lest they get certain attention they'd rather not receive...
This or that only guildes have typically not been the most successful from what I've seen (outside more mature guildes that don't want to have to worry about filtering guild chat for younger viewers, read dirty jokes, or to have to deal with certain drama such as this 1 9 year old. That person's thing was to ask in the most nasely and whiney sounding voice that had not dropped (kinda ear piercing like) to be invited to a raid that formed before he joined, every 30 seconds. Peeps weren't happy about the spamming of the vent's raid channel as such, and even the MT who was 14 commented "I might not be 18 yet, but I don't think I was ever that bad", and "he's annoying, can we kick him now?"
I've seen some try to make druid only guildes, hunter only guildes, pally only guildes, etc... And naturally when it comes to runs; well hmm. There's always the thing this or that class can't do. As to women only, it's not that many go out of their way to lie about their gender; but on the other hand they don't want to draw attention to it either, especially if it could mean someone hitting on their Belf, etc.