I bought a foal this year - I didn’t search any of the websites, it was solely through facebook groups (the dressage breeders’ group, the WB foals for sale, and the dressage horse sales groups). The only sales site I’ve looked at in the past year or so has been warmbloods for sale because I can search by pedigree. Ads themselves were highly variant and I developed some things that really stood out in a positive way, and things that immediately turned me off ads.
The cons: the biggest pet peeve for me is advertising a horse as “(SOMEHOW RELATED TO) (A BIG NAME HORSE HERE - Sandro Hit/Donnerhall/Weltmeyer/Jazz/Ferro/Etc)!” It makes me feel like the only way they can sell this baby is based on the biggest-named connection in the pedigree - regardless of how close the connection is. (If one of the above is sire or damsire, fine. But if it’s an oblique relationship? No.)
Everything NA-bred/marketed seems to be an FEI prospect, per the ad. At this point, saying it’s FEI quality or has main ring potential means nothing. A majority of ads say something to the effect (“Professional quality” “FEI quality”) and it lost meaning.
The ads I liked a lot: Straightforward information that wasn’t emotive.
Sire/Damsire/Dam’s Damsire with height and performance records given on all three stallions, height of dam & performance record if she had one. I also found it helpful when ads gave information & photos of the dam’s other offspring (I can search foal crops by stallions pretty easily, so didn’t really find this information necessary). Height, performance record, trainability & temperament on the dam’s other foals if you have that information = super great!
Frank assessment on personality/handleability. How do they react to new things? How easy are they to teach new things?
Gaits was more of a “video preferred” thing (there’s no uniformity to how people describe gaits, I found!) but if horses are uncooperative and video was hard, then information on rhythm (natural cadence or no?) balance (sit/drive from behind or no?) and way of going (flat/sweepy, or more articulation?) Descriptions of suspension in young horses is especially variant so turned into a bit of a white elephant on most ads, but I know some people appreciate seeing it included.
As far as imaging goes, two or three quality images - a portrait, a conformation shot (flat ground, feet unobscured), and if it exists, a really exceptional trot or canter photo. Quality video (in focus, smooth) that covered the basic gaits. It could be 18-20 seconds with just a few strides of each, but quality. In focus, not grainy/fuzzy/shaky.
And definitely keep updated images/video - it can really help buyers see how horses are developing.