I think there are a lot of girls that squirt only sometimes, so it would have to be at least a triple choice (yes, no, sometimes).  

I am a very consistent squirter, so I advertise it.  But I've met quite a few men who say something like "[provider's name] said she can squirt, but she didn't with me."  I've also seen girls claim to squirt on the boards (especially when responding to ISO posts), but when you read their reviews, there is no evidence of it whatsoever.  So it may be a difficult category to accurately classify girls in.

I know someone that it's guaranteed, someone it's been 2 out of 10+ times.   It's always a pleasant surprise.

I agree there should be an option for squirting, with the yes/no/sometimes options. It would cut down on the volume of reviews I have to find them quite considerably!