And a non-trivial amount of ongoing expense - water, detergents, maintenance, cleaning, etc.

There is usually no timer based coin-op for washer, they are programmed to pay per wash cycle. 10 minutes isnt long enough to rinse out the detergent anyway even if that was a thing:) Only dryers pay by dry time, but usually even those usually require a default 40 minutes for example and extra quarters would add increments.

I do use bleach after washing to spot treat anything that got left behind stainwise.There are some comments about stains not coming out, but I am guessing they don't use a premium detergent.

Granite is available in a wide range of colors, patterns, and finishes, and it can add a touch of elegance and sophistication to any kitchen or bathroom.Benefits of Granite:Durability: Granite is one of the hardest natural stones, making it highly resistant to scratches, chips, and cracks.Heat-resistant: Granite can withstand high temperatures, making it ideal for use in the kitchen.Low maintenance: Granite requires minimal maintenance, and regular cleaning with a mild detergent and warm water is sufficient to keep it looking new.Unique: Because granite is a natural stone, each slab is unique, with its own distinct pattern and color.Drawbacks of Granite:Porous: Granite is a porous stone, meaning it can absorb liquids and stains if not sealed properly.Cost: Granite can get expensive, especially if you opt for a rare or exotic variety.Installation: Granite is a heavy stone that requires professional installation, which can be costly.

This will be a place they can put their detergent, bleach, etc or even to store some folded towels etc.

They are fully furnished, right down to pots & pans and laundry detergent.

@Shane Siederman Thanks for the reply brother i really appreciate it. im thinking whirlpool commercial washer and dryers all coin operated, all together im looking to have 10 bedrooms so im thinking 4 washers, 4 dryers. i also looked into a used vending machine that i can stock with detergents and dryer sheets. looking to make a little money where i can all while providing a service. 

I deduct washers, dryers, laundry detergent, soap, toilet paper, light bulbs, linens, towels and my promotional pens and adult oriented calendars.

I had to buy some towels, detergent, pillows and sheets; but those are pretty minor items. 

Then, clean up the mold with Dishwashing detergent mixed in water (it does a better job removing the root of the mold).