Vanity sizing or mislabled?

Yep.

Old Navy is especially bad in this respect. Pick up a pile of 34 W 34 L and they're all over the place, size-wise.

Levi's hasn't been as bad but it definitely was not a matter of just getting 34 W 34 L (the size of his last pair of Levi's) and leaving it at that. He had to try 'em on.

In order to determine if these pants were mislabled I believe we need photographic evidence.
Before and after shots (preferably rear) will do nicely thanks.