This may or may not count as a valid data point, but I can tell you that nerd-related temp agencies (e.g. for software testers and engineers) do not skew towards the attractive. 
Another data point: the recruitors and intermediates at Dutch temp agencies also answer to the OP’s desciption. They are young, cheerful, outgoing, goalgetting, almost bossy girls.
Being female, I can’t really say if they are more attractive then average, but it may very well be.