Used to use Glassdoor, but it has become progressively more rude/pay-walled over the years, and they allow more paid employer astroturfing than they used to.

I suppose that's just a sign of the times, and I don't necessarily have a grudge against the company for doing so. It does however mean that the site is no longer useful to this end, at least for me.

As for directly contacting a company, I tend not to. Sometimes this works out, other times not. I thought I would hate my current job and thought I was quite unqualified, but it turned out to be pretty fantastic. Just going with the flow sometimes works out that way.