I think it's particularly troublesome when you're browsing the sales section and they have it in half yards. They'll say something like "on sale $4.95" ( and then that means by the half yard.) Maybe the "sale" meant they knocked off just a few measly cents of the yard price . It hardly seems like a sale when when you're only talking about a half yard.
I don't mind doing a little extra math for a good deal but I'd like some websites to be a little more upfront.