Mike … There are no services that I know of that track whether a property is rented or occupied by owners. Although the owner’s address in FR (and in tax records) is a tipoff. Clearly if the owner’s address is different that the subject property, that’s an indicator that it might be rented.
There are plenty of threads on FR that discuss the eviction process and the distinction between owners and tenants, Ex Here > http://goo.gl/WqUl7 and Here > http://goo.gl/8fScl
One rule of thumb that can keep you out of trouble is to always make a point of going to see any property you might be interested in bidding on… I have violated this rule only on rare occasions (and I do not advise anyone to break this rule), and usually it’s when the property is/was recently listed and there are good photos inside and out … But it’s always a good idea to kick the tires so to speak.
During your drive/walk by, there’s a fair chance that you’ll encounter owners/occupants. There have been occasions when I’ll introduce myself to the occupants. (NOTE: I also research the owners ahead of time, via Google and other resources, and would not introduce myself to any ex-felons, particularly violent offenders).
I strongly prefer the straightforward approach … “I saw that this property will soon be going to foreclosure (trustee sale) and wanted to know if you can share any information about that?” You will sometimes be met with a Clint Eastwood scowl and a “get off my lawn” (in so many words). But if you respond to any hostility with politeness and honesty (explain who you are [first name only] and that you’re an investor) … in a surprisingly high number of instances (certainly not always) the owner or occupant will relax a bit and share information. Frequently they are very anxious and curious to know more about the trustee sale (they often have no one to talk to about their predicament) and you can educate them a bit. In exchange they may share more about their situation and intentions (anything from total capitulation to ready for battle).
Again, while I have had some success in speaking with owners/occupants before an auction, you need judge each situation before making direct contact. Follow your instinctive “little voice” … is this safe of not? If someone on the front porch has a scowl on their face and forehead tatoo, then maybe not. If your voice says “not” then walk on by.