We see mis-listed units all the time, but occasionally there's actually an additional one per the assessor. 

Hence the lot on which the house resided was taxed at a 45% discount based on actual value, while the tennis lot was taxed at about 4 times what it should have been by value. 

And that's just a 2 unit, obviously the numbers creep closer to actual investor-numbers with a 3 or 4 unit pumping in more rent.

Some properties actually lose money each month but gain value through appreciation.

One last question - is your assistant actually hand writing the envelop?

When I subsequently asked the tenant over the phone how many cats she had she said four, which is likely half the number she actually has, but is still a lease violation.At this point I feel like it’s pointless to even ask if the cats are neutered (and therefore less likely to spray urine on walls) because clearly she is willing to lie to me and her attitude seems to be that she makes the rules not me or the lease.

In your situation there is actually another factor that may work in your favor.Only the proceeds allocated to the sale of the building can be used in a 1031exchange. 

The reality is that you will not find that in the seller finance space, and even if you do, there will be virtually no discount. 

I actually aim for not having any one real estate investment make up more than 1% of my net worth.

Everyone thinks they can paint but there's a big difference between a professional paint job and a non-professional one (the latter usually actually damages the property instead of improving it).