Typically they're experts, so you want real solid numbers...or they will flush you out if they think your numbers are off.What are you protecting yourself from?  

I've also used word of mouth when I am flush and ready to buy.

Flush every toilet, turn on every light, faucet, appliance, etc. if it's all in order, then they give you the keys and you give them cash to go away.

You can shoot for ultimate zoning density, but if you have no way to flush the toilets you're dead in the water, no pun intended.

The plumber flushed out the pipes and all seemed ok.However, the tenants have reached out again saying that the dishwasher has been showing an error since.

The biggest thing is time and demands of the investment for the return you are trying to produce on the asset.I have some clients that will take an easy 10% cash on cash return with 4 national tenants and 1 to 2 mom and pop versus a hard 12 or 14% return where they are dealing with constant turnover and issues.Those already flush with annual income tend to be very busy and do not have time to work for extra yield.Example: No headache 1,000,000 investment at 10% cash on cash = 100,000 annually pre-tax before other metrics for increased yield.Example 2: Headache with more mom and pop tenants and lot's of them to deal with.

It probably slows down my ability to buy a pure investment property, but it gets me out of flushing thousands of dollars down the toilet each month and gets me into an appreciating asset, and it helps me save more than $1,000 in disposable income each month (not even including principal paydown).

If they were flushing golf balls down the toilet, yes.  

THAT will leak only when flushed.

Water heaters, I have flushed and if they aren't starting to rust, same thing I keep them but I place a water alarm by it just in case.