Don't get me wrong, I don't mind buying through a reputable retailer. In fact, from what i can see in both briars and meers, several very reputable retailers carry some of the better results of certain carvers while I see the carver selling directly through sites like etsy and you can see some of these pipes aren't quite as a good as their other work.
Probably my biggest concern is every ad for a meer, it seems, lists the the pipe as being carved from "High Quality Block Meerschaum" but without it being in hand there is no way to actually tell the quality of the material. Also, as mentioned by others, due to the way the ad is listed and the pipe photographed, there is often little or no information regarding chamber dimensions and/or stem and tenon material or even if it's a screw in stem.
Plus, I like knowing something about the maker of the pipe. Especially in figural meers I like to see the carvers name on the pipe stummel. For classic shapes I'm okay with a company logo or identification mark on the pipe stummel or the stem. A name, mark, or logo lets me know what I have in my hands when I'm holding a pipe.