The futility of reference checking

This isn't in reference to my recent new tenant, more a general comment that I wanted to write about for some time.

When a new tenant applies, you always ask for references. Seems like the right thing to do. But how many times have you called a reference and you got a bad report? Rarely I would guess is the general answer for everyone, and it is for me as well.

Lets break this down a bit. A good tenant will have no problem providing a reference, and their current landlord will probably say nice things (keeps the place clean, pays on time, etc). But a couple of different things could happen with a bad tenant:
1) The "my current landlord is a Nazi" excuse. You meet the prospective tenant, and things seem pretty good, but then you ask why they are leaving their current place. Then the horror story comes out, with stories about how bad the current landlord is and how he has kept the place substandard and it's doubtful they will get an honest referral so they beg you not to call. This is usually corroborated by a couple of other friends or maybe someone "respectable" like a minister or something. So already you know that if you do call you will probably hear bad things. So what do you do? By passing you essentially are telling these people you think they are lying. Maybe the right thing to do is pass on the situation. Maybe I should have done this more often.
2) The landlord who just wants to get the people out. Here's a case where the tenant is a monster, and essentially the current landlord has agreed not to say bad things about them as long as they will leave. Sound really unethical but believe me it happens. So you call this guy and he says they were decent people and paid on time. You wind up signing these people up, and then you discover the monsters that they are. I had evict one tenant that was like this. Only when she finally left nobody called for a reference. She probably used tactic #1 above.

So I think checking references is a somewhat problematic practice. On a couple of occasions I have called a reference and they gave me glowing reviews, and those reviews turned out to be correct. But it still makes me wonder.