I have had a couple of bad experiences with separate businesses that make me wonder if it's ever appropriate to leave a review without having actually utilized their services.
In the first case, I called to inquire about a type of medical testing that I wanted to be done. No one answered, and there was no business voicemail set up. The woman who called me back (I didn't leave a message) was incredibly frazzled, and began with "Yeah, did I miss a call from you?" I set up the test anyway, and had to remind her two or three times over the course of the conversation the dates and times that we had agreed on. At one point she said "We used to do [more expensive test] but we don't offer that anymore" and I became quite alarmed when I asked what the difference was and she blithely said "It's more expensive but it's much more accurate, you know, pros and cons..." She took down my information (which took a long time, because she was also incredibly hard of hearing) but I never received any sort of email confirmation that we had spoken, or that I had an appointment scheduled. After thinking it over and deciding that I didn't have confidence in her, I emailed to cancel three days beforehand and still had no reply. All in all it was an incredibly odd experience.
The second business was a language learning institute. I had to submit an email inquiry to receive any pricing (already annoying) and received a call from them in the middle of the work day. The receptionist smacking gum over the phone began with "This is [language place], you wanted to learn [language]?" When I told her that it wasn't a good time for me since I was driving and asked her to call me back in an hour, she became combative, sighed heavily, and said "I'm off in an hour, are you sure you can't talk now?" I replied "I'm still driving, so yes, I'm sure." This stumped her and I had to suggest a different day, and then negotiate a time slot. I never received a call at the expected time, which leads me to think that she expected me to call her instead of the other way around.
Normally I wouldn't review somewhere online unless I'd actually used the place in question, but these two places got under my skin more than a little bit so I'm curious as to what other people have to say.