I think one of the best indicators is median price vs median income.
For instance, I make the median income for my area, but the median priced home is nearly 8x that much.
Considering the traditional, 30 year fixed rate loan products (which is the only one worth considering imho) — which states that you can borrow roughly 3x your yearly gross income — prices are thoroughly out of whack.
If the average Joe can’t afford the average house then we have a problem.