Be cautious and ask lots questions.

I would also be cautious who I read/listen to and take advise primarily from seasoned investors, who have successful track record and something to back their experience with a number of properties they own, vs those "fluke" or one-two times high fliers who imagine they are pros after 1-2 flips and spew their advice. 

I have been a Bigger Pockets Pro Member for a few months now and am really trying to be cautious while trying to make my first deal with an investment property, but realize that a deal is never going to be as good as I hope.

I just went through a similar process this week looking at 2 duplexes in Kitchener and making an offer on one, which was not accepted because I was very cautious with two of the things you mentioned, no lease for existing tenant and zoning/title.

I will move cautiously with this potential tenant.

we worked off set amount of dollars per deal... we were cautious to make sure all of our costs (hard money, holding, etc) were in factored accurately and we did great.  

I would be very cautious about cash for keys.

Should you be cautious, of course.  

We mostly work with buyers that we have relationships with, so we don't have to be so cautious, but most of the times you do have to take certain measures to make sure you get paid.

The average homeowner is in better standing than before the crash in 2008, but are investors being cautious, or have some overstretched themselves, and possibly entered into a space they have no business being in?