They also left rugs, poop scoopers, and kitchen gadgets behind.

You are training a gold fish to climb a tree and when you see it is hard to do, you will equip it with gadgets to try to make it work.Instead go invest in a monkey!

If you can't do quartz, I would still look at replacing the countertop with new sub-surfacing that can accommodate an under-mounted sink because it has a very high end feel that tenants will recognize when comparing photos of rentals online (add sink garbage disposal at that time if one does not exist already, it's a walkthrough gadget that helps sell and keeps your own maintenance down). 

I'm pretty sure when he spends the night he is vaping in the tenants room.

I have waited on the gadgets for kids and have my son do that as he knows what's hot, I don't have a clue.

If you were buying a tech gadget for your business, I would agree - only do it if it helps your bottom line.

Does anyone with a no smoking policy allow tenants to 'vape' inside of your rental property? 

Newest tech gadget?

Disposal of fluids can be done properly, it's when they aren't you can have an issue.Noise is another issue to be covered generally, so revving up an engine constantly (as if they think they know what they are doing as old hot roders did) can be a noise issue.My lease prevented the tenant from keeping any inoperable machinery on premises or parts thereof, which meant all vehicles, lawn mowers or any gadget had to be operable, vehicles had to be titled, licensed and insured.The outside had to be free of clutter, trash, salvage or personal property not designed specifically as lawn furniture or for outdoor cooking and such was to be stored from view from the street when not in use.Those types of covenants will take care of a vehicle on blocks or an engine sitting in the yard.I wouldn't say anything about some minor repair being made to a vehicle, where do you draw the line, changing a windshield wiper or adding fluids or pulling the transmission. so long as it's done in the day and operable, doesn't cause toxics to spill, doesn't produce unwanted annoying noises, isn't a safety issue, is kept clean and neat, what's the issue?

Baah - here's my new toy, new trip, new clothes, new gadget.