I get that a fair bit too - my "favourite" one was an angry message telling me the item was so small the buyer couldn't use them and now had to buy different ones, leaving me to wonder what they expected from an item when the first word in the title was "tiny" followed by the precise measurement (not to mention my images showed them to scale). There seems to be a few people out there that don't even bother reading titles or looking at photos before buying.  I even had one who purchased something 50mm long, then purchased the same item at 40mm long, and complained (only in feedback) that they were shorter. >_> (I mean, I've made mistakes like that a few times with items, but I always double-check the listing first, discover it was my fault, and kick myself for a little while. I will never understand the ones who just decide everything is the seller's fault). 

With regards to clothing, a lot of people think that if they buy something and it doesn't fit them, it's "not fit for purpose", which is simply not true in the vast majority of cases. If a t-shirt functions as a t-shirt, it's fit for purpose; and for it not to be, it would need to have a flaw that makes it unwearable by someone, eg one of the sleeves is sewn shut or something. The only way an article of clothing that doesn't fit someone becomes "not fit for purpose" is when the retailer explicitly states it will fit them in particular, and I don't know of any B&M stores that will make those kinds of promises, let alone online ones, unless they are tailored items made to order.