It can be as simple as driving by and looking at the yard or a comprehensive assessment of everything inside the unit.

By far the quickest and most comprehensive way to pull comps and create a CMA is using the MLS.

Aside from providing the basics (ie. listing tool to get the property published to 10+ major sites, scheduling tool to schedule viewings, tenant screening with comprehensive applications -- pulled reports from TransUnion, which include nationwide criminal background checks + credit checks + eviction history, digital lease creation tool, rent collection tool, and maintenance tracking tool), your tenants have additional capabilities which makes it an easier sell on your end when getting them to transition over (ie. their ability to report on-time rent payments to the credit bureaus; this can create an added incentive for making sure they pay that rent on time).

I have also had various household appliances interfere with the signal on occasion.

Filing status – would need to figure out his filling status single, married, head of house hold.4.

Proper was marginally more expensive but covered the business in a more comprehensive way.

They have comprehensive info for investors looking to get into the game.

I hopped on this thread to add my two cents, but saw @Chris Coleman had already given a comprehensive answer. 

Comprehensive reviews from research and information giants that compile metrics have also supported the strong potential for the overall trend to persist. 

Or Refi for 15 years to ease the pain in our household income.OR2.