I know a couple who have two dogs, same parents. Um, one is almost 13" the other is a whopping 22". The parents are on the smaller end of the standard. From what I know, I thought the size was all a guessing game. Well, educated guess, but still a guess.
IMHO, I'd probably do more research and even then, I'd most likely walk away. Using the term "cute sized", right there, tells me she's trying to SELL them as "mini". I'm not saying her line is bad, but I'd be concerned of what she's trying to accomplish.
Sigh. Just me personally, I'd probably walk away. But I'm sure you know a lot more about her, so you need to make the call if she was just being silly, or if she's selling them as "mini" without calling them that.