I bought two BP morphs from Ed Clark (a lemon pastel and a cinny pastel) I'd paid them off awhile ago, and had been waiting for proper weather to have them shipped.
I recieved them this morning, and they were packed well enough, the heat pack was warm and all, though both snakes were in the same snake bag. I've recieved shipments with multiple snakes before and they've always been packed separately in the box.
Anyways, I discovered mites on the snakes, especially on the cinny. As we all know, mites are a great way to spread diseases among collections. Luckily I always keep provent-a-mite on hand so I was able to treat the tubs the snakes are in, but even so, the risk of one or more having escaped the provent-a-mite (ie falling off the snake bag etc before I sprayed the PAM) is real, and I sincerely hope they don't spread to the rest of my collection.
Ed claimed he did not know of the mite infestation, which very well may be true, but I believe you should keep close eye on your animals.. mites are not difficult to spot.
So.. those are my experiences.