Well, all I can do is add a personal experience. I sold a Selmer Serie III Tenor saxophone with a "like new" description and no photos recently. The buyer was very satisfied. Delighted, I might say.
As a contrast, I recently offered a mpc to a forum member who was on a search and I thought I had an outstanding mpc to offer him, which I did through PM. I did not have it up for sale and was not too keen on letting it go, but I thought I would do this person a favour since he was in a quandary. We played "stump the dummy" over a number of emails while I answered all of his questions. Additionally, I had to provide some additional information (which I won't go into) to prove my reliability. When he asked for photos, I told him I was a lame photographer and anyway, how can you "see" how a mpc is going to play? But I then offered up endorsements from two other very fine players about the mpc in lieu of photos.
After he seemed satisfied, and agreed on the sale, then he wanted me to wait until he got the money to send. OK, I can do that. Then I got this email out of the blue asking for studio-quality photos and a recording of the mpc, at which point I said, perhaps this is not a good idea. Good luck on finding a good mpc for yourself.
I could've jumped through my @ss getting studio quality recordings and photos (I don't have any recording equipment available and told him that) but, due to his indecision and back-tracking, it's quite possible that once he got the mpc, if it didn't work for him like it worked for me, that he still wouldn't like it and then I'd get grief over that, too.
There is a contrast here I'm trying to make. In the first instance someone got a $3000.00+ instrument from me on my word and was very happy with it. Everything went very smoothly. I could have provided the second person all kinds of reassurances and photos and recordings for a $200.00+ item and still he was reluctant to believe me. So my reaction is, why bother in the first place? Either I have credibility with you or I don't and sometimes offering all the additional support material in the world isn't enough.