Also, you can contact the local supply houses and ask the counter men how the company is with it's people.
Word gets around...
There are online registries which list company info, for ten bucks or so ... along with assets etc of the company.
Also check with the Better Business Beureau.
Check with the State licensing board to see if there have ever been complaints filed against them.
See if they belong to the Chamber of Commerce.
Does the outfit support the local chapter of RSES?
If so, check with the chapter president. They should be listed online via RSES's website.
Check with the labor board. See if there are any past issues dealing with employer/ employee relations.
This is sometimes a fair indicator how management treats it's most valuable resource. (it's employees)
If ya need more info, I have some more ideas. Let me know.