Hard to see how people would be willing to pay the same price of an asset before the covid noise vs today..

But, two college kids can cause as much damage (and more noise) than a family with well behaved kids (or dogs).

These and other efficiency, comfort, and noise issues are readily resolvable and should not be considered as part of the normal operating condition of a steam boiler.

Call the police and register the noise complaint. 3 strikes your out.

All of a sudden they are complaining about all kinds of maintenance issues, you end up in and out of the apartment a bunch of times with them complaining about pests and mold and funny smells or noise - you name it - instead of just asking if they can break the lease.So, I'd start there. 

Ignore/laugh about the crazy texts and look for the signal through the noise.

I can tell you the one provided by BiggerPockets is more than sufficient, it's already made, and it's been vetted for your state law.Buy it, use it, and focus on more important things like developing your process for unpaid rent, noise complaints, unauthorized pets, etc.

Tenant complained that the wall AC unit upstairs does a loud humming noise.

Not enough responses = priced too high (assuming your marketing is dialed in).  10 showings w/out an application = something is wrong with the unit (cosmetically: not clean, didn't replace blinds, etc = clean it up more) OR (functionally: unit has issue that comparable units in the neighborhood don't have - street noise, weird layout, etc = lower price to combat issue).  

Our nightmare tenant also resulted in other tenant complaints, cops being called for noise, parking crazy in the parking lot taking up two spaces, destroyed carpets where they let cigarettes fall and burn on the carpet (and smoking wasn't allowed), her baby daddy moved in almost immediately - it can result in lots of time dealing with complaints and problems and I almost lost good tenants, too, who I had to assure I was getting rid of the nightmare tenants.