But while they are there, they look around for anything else that may need to be done and also just over all check on the property and if tenant is obeying rules (like pets for example). 

How do you avoid parties and unauthorized guests/pets?

Zillow sends an email with the person name and profile info (if they filled it out), which has name, number, income, pets, etc.

As many tenants will tell you to your face that they do not have a cat or dog, and then try to sneak them in...What about the following idea: Ad text say "pet friendly" Seems people are more likely to reveal pet ownership that if you say "no dogs/cats allowed."

You can (and should) make them pay full security deposit, any pet fees (but probably no pet rent, unless you are under the Sec 8 rent) and do full credit and background checks (there will be debt, maybe collections, but you can screen some criminal, depending on where you are, and evictions -- again, depending on where you are).Let's say you are charging $800. 3 times is $2400/month.

For room rentals, do you allow pets?

I often allow pets and have had some great tenants with pets, but have occasionally been left with smelly apartments.

I also think you are parroting some things you've read in books or heard at seminars that rarely, in reality, work out.

Cops have also been inside the house and have witnessed signs of extremely unsanitary conditions: pet waste/urine around the house, you get the picture..

(This is an added perk, because I get time with my dog and prospective applicants tend to tell me all about their pets.)If you have a friend of colleague who can travel with you, that's great.