A few things, use hydrogen peroxide on the basement, it'll get more of the mold (goes deeper) than clorox.

It's like asking is there an oxygen atom and two hydrogen atoms in a molecule of water?

Often this stuff can be easily eradicated with a combination of bleach and water or (better yet) hydrogen peroxide mixed with some water.And, as Adrienne has mentioned, the stuff in the kitchen can be caused by cooking methods of tenants. 

Intel is a great example, who is building the largest chip manufacturing plant in the US right here, and it will be a $20 billion dollar investment that brings a few new thousand jobs.https://www.dispatch.com/story/business/2022/01/21/intel-ohio-building-computer-chip-factories-licking-county-jersey-township/9173472002/ Another example of economic growth is the upcoming Ohio State University Wexner Medical Center Inpatient Hospital which is a 1.9million square foot hospital that will bring over 800 new beds and a thousand new jobs. https://abc6onyourside.com/news/local/new-osu-hospital-expected-to-transform-health-careHere are a few more recent investments https://www.10tv.com/article/money/business/hydrogen-power-company-hyperion-bringing-700-jobs-to-columbus/530-25907aab-5517-4661-a9f3-d2ed2d5be6b0 https://news.wosu.org/news/2022-02-08/rumpke-to-build-50-million-recycling-facility-in-columbus Check out The Complete Guide to the Columbus, Ohio Real Estate Market which goes through the Columbus, Ohio market in depth and will give you a better scope of where the highest levels of growth are taking place and where to look to invest.

Starting to feel like this is bigger issue...https://www.nbcnews.com/health/vaping/tests-show-bootleg-marijuana-vapes-tainted-hydrogen-cyanide-n1059356Also other issue, a lot of smoke alarms triggered in his apartment. 7 alarms in last 5 or 6 months. 

I am one of the Originators of the transition from fossil fuels to clean energy, over a 6 year period was responsible with approx $400 million for building the NY solar Infrastructure on Long Island, changing policy and laws as well as working with all Trade Associations which resulted in towns incoporating Energy Star Homes into law, made LEED standards, transition the lights to LEDs,  played a big part in construction of the first Solar Hydrogen home in US, involved in ES, wind, Electric Vehicles, Battery Storage, new and retrofit commercial and more.Over my career I have encountered every possible technology, good bad and scam.

Those you need to clean first with something like an equal mix of Dawn, hydrogen peroxide and baking soda.  

What I did, and it worked perfectly, was I got a gallon of white vinegar, baking soda, hydrogen peroxide, and mixed some of that in a 5 gallon bucket.

Don't even breath (literally) the idea that some mildew/mold in a bathroom gives a tenant the right to vacate the rental unit.Bleach will remove this but a mixture of hydrogen peroxide in a little water tends to kill it better.Gail

The rotten egg smell is an indication of hydrogen sulfide in the water which can occur naturally, but is very corrosive and can cause problems with plumbing and fixtures.