They are just looking to diversify their wealth and/or create another stream of income for themselves.With that being said, I do agree that the mentors and gurus online are selling snake oil when they make it sound like active real estate investing can be a passive source of income.

Makes no difference to me, we've had hamsters, gerbils and snakes reside with our tenants.

Is a snake in the yard considered part of pest control?

The problem that most newbies have is just what you are encountering, the gurus say go out and wholesale and be profitable(in thundering voice) and that is what you try to do.

If you live in the unit get a short, no more than 20 foot hand snake with a drill hookup, they are about 10 bucks and handy for short runs to clogs.

No worries about pest control & exclusion - large rodents, birds, bats, squirrels, or snakes using the Santa Claus home entry technique.

And occasionally a backup occurs in between those routine snakes.

Not really sure what your goal is in regards to making your life more difficult.There is no logic in a pet owner buying a rattle snake to experience a snake bite.If you want to do section 8 modify your screening for that purpose, concentrate on credit history and previous landlords as most on welfare are not measured by income. 

The guy who owned the house before me told me he has had to run a snake down it to clean it out.

Remember that part of your success comes from people knowing they can trust you, that you do what you say and that you operate in a way that will not attract unnecessary legal or regulatory action.Too much reading between the lines leads people to think that there is a snake in the grass so they will not trust you.Find a good agent that can run automated reports.