Not to mention the sneaky way of using models for plus-size clothing when they are either clearly not plus-size, or if so, it's just the 1x range. It's a crapshoot as to what will actually fit. And women aren't necessarily symmetrical. Plus-size does NOT mean you're endowed like Dolly Parton.
I kind of feel sizes have changed in general, perhaps due to changes in how they're manufactured, so it definitely is a crapshoot. I find that I can't simply buy the same size between different brands as it's not a guarantee that they'll fit. For instance, a size large of pants from one brand will fit well, but another will either be too big or too small, or the proportions will be wrong.