An example would be no custom showers like the one in this post and using tub/ shower inserts instead.  

Seacoast NH, for example, has some great potential with short-term rental markets (Airbnb, VRBO), especially in towns like Portsmouth or Hampton, but the regulations can be a bit tricky.

For example the license should not only have a cost but also require at least some compliance training targeting some of the most common issues/complaints.

Example if you buy a new build at 300k or a renovated 100 year old home at 300k right next door, both should see the same appreciation. 

For example, most Developers in the Seattle area are taking many properties and turning them to condos since that is a booming market with high rental rates And sometimes more conveniently built and accommodating then a SFH.

For example, minor towel or linens replacement is something I have a budget for (built into pricing).

Also, keep in mind if it causes an undue burden on you or is too costly you can deny them. for example, if your insurance company says that dog breed is on the ban list then you need to find out how much it will cost to insure them. if the rates go up because of the dog then you can deny them based on the undue burden. 

Regarding #2, do you have an example of what is defined as the "property code"?

Quote from @Lorenzo Lopez: In terms of buying my first deal, I haven't been able to move the needle because, where I am, for example, small multifamily is trading at around 5.5% caps and rates are 6.5% .

You can hear real-world examples of how others have built their investment portfolio and (hopefully) learn to avoid their mistakes.4.