It's just that those other agents didn't like their business practices.

When I'm practicing underwriting, I'm finding a property that looks interesting, trying to find out median rates in the area and do some math to get to the NOI then divide by 6% and come up with some sort of value.

As mentioned above check your local laws regarding STR, occupancy, building code etc.If good on the above, then figure out your cost. 

When I posted on a different website someone stated that there are different laws in every state.

(A good example of why you should work with an STR-friendly agent who knows Airbnb laws in and out. ... ;))Anyway, what OP is looking to do is legal in Littleton.

https://www.kts-law.com/practice-areas/landlord-tenant-law/Good luck!

Definitely encourage you to practice analyzing a few properties using the “Deal Finder” at the top of your screen, and the Calculators (Under “Analyze Deals). 

However, in practice, holding the replacement property for at least one to two years is often recommended.

California has had statewide ADU laws since 2019.

@Brandon Walston - Every state has their own landlord / tenant laws, but I think pretty much all of them (or maybe even at the federal level), you must honor the lease that is in place when you buy a tenant occupied property.