Honesty. Don't tell me a horse is a "champion," but then when I go to look at the results, the only time the horse won that title was when he was in a class by himself. I WILL stalk a horse online if I'm interested. I'll look up pedigree, show record, show proofs, videos, etc. Nothing can be hidden from me ;)
Pictures, I just need a decent one. It can be a nice head shot, confo shot, under saddle, whatever. I want SOMETHING to look at. If a horse doesn't have a picture, I ignore the ad.
I'm not big on the four square conformation pictures, honestly. I want a video. I want to see the horse moving, no slow mo, etc. If the horse is a riding horse, I want to see it under saddle with no training tack on it (aka it needs to look like it would when you were showing it).
I've bought three horses off of videos and limited (but GOOD) pictures, and all three are great. No complaints from me.