Normally you as the new buyer are obligated to honor any existing leases or option agreements. 

He had some personal things going on and essentially gave me two options: go myself and he'd give me the code to enter, or he could ask another agent to show it to me. 

I realize that this is a done deal now- but when you buy a property with leases in place then you are legally obliged to honor those leases.

You could also check with your local code enforcer about the pool and renters.

For example, https://library.municode.com/HTML/13893/level4/COOR_CH5BUCOREAC_ARTVIIHOCO_DIV2MIST.html which describes detailed sections on what a code or building inspector (or potentially an appraiser) will reference if they cite your property (cite your site).

One time they just let a county inspector in who just popped up to make sure things were getting done up to code (thankfully everything was okay). 

Ask them what zip code they're interested in buying, how many bedrooms and baths, and what's their price range.

@William Robison  that's very honorable and I'm sure went a long way with those people who hopefully will think of you when they DO need to sell or know someone that does!

@Ryan Hobbs Research CA probate codes 10402 and 10552. 

If only one you may be able to add just another shingle layer to it for cheap.If there are a ton of shingle layers which usually shouldn't be more than two then you put undue stress on the structure and you might be in a county or city code violations for unsafe practices and conditions.The next thing you need to do it go to your attic space where you can see the under board of the roof and it's condition.