You could evict, create a pet lease and charge for the dog, make tenant get rid of the dog if they want to stay, or request tenant break lease and leave without eviction. 

If it is universal that only leaves me with one more home to buy before I need to start looking at other funding options. 

If he doesn't keep good records, then you have a bit of a problem, and will have to calculate it yourself.Finally, with all the information you've collected, you determine if it is a good deal or not.Based on what you listed above here's an example ballpark monthly budget:Principle & interest: ~$1,000 ($195k loan @ 5%)Taxes & insurance: $300-500/mo (depending on your locality)Utilities: $200/mo for water (most 4-units has the owner paying water)Vacancy: $140 (based on 95% occupancy at $2800/mo)Maintenance/Capital expences: $280 (standard 10%)Management: $280 (10%)Total: ~$2,300-2,500, leaving you with a profit of around $100/door, with only $10k invested. 

If you are living in the condo and have decent income and ok debt to income ratio I would get a conventional loan on a rental property and leave the condo alone. 

Just make sure you use a 1031, and leave enough for the down payment on the new place. 

But then I thought, if I dispute it, it could bring my property taxes up (0.79% assessed value in CA).Should I try to dispute the improvement vs land value or just leave it as is? 

Did he leave his wife? 

He has offered up front to have the floors refinished when he leaves.

It needed a lot of work to the "guts" of the house (crawl, electrical, plumbing, etc), but we were able to leave a lot of the cosmetics alone which the bank had actually replaced not too long before we bought it.

If they are invested in stocks bonds or mutual funds are are accustomed to 4-12%...and you double their return...you're likely still leaving PLENTY of return for yourself.