One of today's callers presented an interesting question. She sold a yearling colt that she thought was a blue roan. It was certainly possible for him to be a blue roan, as his sire had been a blue roan. She told the buyer she thought the horse was a blue roan, and the buyer agreed with her. After purchase, the buyer decided that the colt was really gray instead of blue roan, and demanded his money back.
As we all know, horse sales are customarily "as is" and buyer beware, unless the seller knowingly misrepresents the horse. Here, it doesn't appear that the seller knew that the horse was really gray rather than blue roan, so the seller didn't knowingly misrepresent the horse. In fact, the buyer had not yet obtained a professional opinion on whether the horse really was gray or roan - he was just stating his opinion.
Every year, we receive a few calls on genetic mistakes. Typically, the call is from a buyer who has purchased a stallion or mare to use as a breeding prospect, and the horse doesn't turn out to be the color the buyer thought or be homozygous for a particular trait (such as the tobiano coat pattern), or the horse does turn out to be a carrier of undesirable conditions, such as overo lethal white syndrome, HYPP or HERDA. Unless the seller knows (or has reason to suspect) the horse's genetic status and misrepresents it to the buyer, the buyer will have no recourse against the seller. It is typically the buyer's responsibility to thoroughly examine the horse before buying, including any genetic testing that may be necessary.