A couple of things:
1. If the property is subject to Los Angeles Rent Control, you can't do STR under any circumstances.
2. The guidelines are strict (which was already mentioned).
3. I'm not sure the numbers really work anymore. Every time I have analyzed a short term opportunity, the cash flow tends to be close to the same as a traditional rental. Keep in mind you are responsible for the utilities, internet, upkeep of furniture, bed sheets, etc. Plus there are the Airbnb fees and some areas have an additional tax. For example I have house hacking clients in Malibu doing STR and the city imposes a 15% gross income tax.
The popular areas (Joshua Tree, Big Bear, etc.) from what I am hearing are over saturated. When there are options, unless your place is extremely special, the only way you can compete is on price. That's not exciting.
Mid-Term Rentals are generally the same concerns as STR, but you could argue less potential vacancy and if the property is subject to rent control, it is a potential legal workaround.
Most of my investor clients are either house hacking, mid-term, student housing, or traditional rental.