My brief experience of dealing with FoI requests involved helping with roughly a dozen that were IT related. And by IT related, after a quick bit of googling turned out to be from sales people at software companies hence the questions about "What suppliers do you use for x", "What is your average spend on y", "How many printers of model z do you have" - pages and pages of it.
Followed by polite reminders that it had to be processed within a certain window. Call me old fashioned, but I don't think that the law was intended to make salesdroids life easier and avoid them having to do work, I'm surprised that there didn't seem to be any kind of penalty for making pointless frivilous FOI requests that took ages to find information so they could then try and talk their way into selling me a bunch of 20 year old printers that are "proven technology mate".
Funnily enough, certainly whilst I was there all those vendors went on my blacklist.
Of course now I'm in presales, at least I know that kind of tactic is a bad idea I guess!