Accessory Dwelling Unit (ADU) that we lease to a long-term tenant on a month-to-month basis for $2,850 per month (inclusive of all utilities), and a 300 sqft.

You'd most likely have to look for a commercial unit, which would be more likely to have the card reading accessories you're talking about + they can keep up with the constant use, which residential units aren't designed for.

Thank you Alan, I was looking for a real sunlight or option to bring in sunlight with a mirror or any other accessories that’s on the market.still appreciated your list of lights. 

A lot of times they will say no.....I then will say, I'm not being difficult but I will ask for clarification, because this is in all of our leases....ANYTHING means, cigars, cigarettes, mar%ua7na, vaping, bongs or e-cigarettes.

The ordinance may require a permit to be obtained for the creation of a junior accessory dwelling unit, and shall do all of the following:(1) Limit the number of junior accessory dwelling units to one per residential lot zoned for single-family residences with a single-family residence built, or proposed to be built, on the lot.(2) Require owner-occupancy in the single-family residence in which the junior accessory dwelling unit will be permitted.

We also have a NO SMOKING of anything inside unit policy including vaping but people will still try to get away with it anyway.

Is an ADU (accessory dwelling unit) in option for your home?

See screenshot below from https://bouldercolorado.gov/services/accessory-dwelling-units. 

Beware of partial / late payments, of pets or smoking / vaping in units that don't allow them, etc.

I'm seeking insights into the pros and cons of investing in Accessory Dwelling Units (ADU) in south bay versus buying a condo in east bay, particularly in terms of appreciation and cash flow.