Is there “vanity sizing” in clothing markets?

Imagine the temptation to sell nominally-marked small sizes (but the clothes are still large) to those who do not "deserve" them.  Does this appeal to self-deception — also known as vanity sizing — occur on a wide scale?   Do we observe ongoing private sector inflation when it comes to clothes sizes? Kathleen Fasanella, a successful apparel pattern maker, says no, it only looks that way sometimes:

Sizes are not created equally; not all mediums from company to company are identical and nor should they be! Manufacturers necessarily target a given consumer profile -even push manufacturers have target demography- and it is more common for consumers of a given profile to share anthropometric characteristics than it is that they not. A medium simply indicates the middle size of a given manufacturer’s size run; that’s it.

…let’s say that everybody had to use the same sizes, can you imagine the number of sizes the western wear company would be forced to carry as compared to the tutu maker? …consumer expectation that they should be able to walk into any store, anywhere and pick out a medium and expect it to fit them but that’s just not reasonable.

Read Kathleen’s whole post, and here are some rough data.  Here is a typical charge, which also names some (supposed) culprits, such as The Gap, Ralph Lauren, and Banana Republic.  I do not have the expertise to evaluate this debate, but I am more generally intrigued by claims that non-uniform, heterogeneous standards are more efficient than pure uniformity.  Note that the fashion industry has never tried "hard enough" to create uniform standards.  I’ve opened up the comments for those who are more sartorially minded than I am.  A related but not identical question is whether movie critics suffer from "praise inflation" over time.