Behr sells concrete paint, you will need to etch, and prime the surface before painting. Not sure of the stink factor, maybe take a trip to Home Depot to smell it.

https://www.homedepot.com/p/BEHR-Premium-1-gal-M500-5-Sojourn-Blue-1-Part-Epoxy-Concrete-and-Garage-Floor-Paint-93001/302354955

Paint will not stick to water. If the floor is damp, the paint may bubble.

Tape a 3x3 foot square of poly to the floor. Leave it for 3 days. When you remove it, if the floor is darker (from moisture) - don't paint it.

The dampness is going to be your worst enemy. An off-the-shelf product isn't going to get you anything but a massive headache (chemically and financially). The things that will work for you:

1. Epoxy specialist who has the ability to do moisture mitigation (please add $5/sf for this treatment) + cost of epoxy finish ($5 - $25/sf).

2. Carpet (yep...carpet with a "breathable" pad = cheap and cheerful for damp basements).

3. Moisture mitigation for the entire basement = $5/sf (if nothing goes wrong) and then you can paint the floor after that.

4. Moisture mitigation + any floor you want

As you can see, you either need moisture mitigation or you go with carpet until you can afford moisture mitigation. It may "look" expensive, but imagine how much HEALTHIER your home will be without all that water vapour entering your basement and causing a "damp" smell to the home (if it smells damp it means you have plenty of moisture moving through....like huge amounts).

SJ what exactly do you mean by moisture mitigation?

Ive actually removed several walls (studs and drywall) a PO put up against the foundation walls because moisture was getting trapped backt here and causing mildew smell + spalled bricks. Ive been advised to keep the foundation walls breathable and basically Im OK with it being the 100 yr old basement that it is - in fact exposed rock + brick walls are kinda cool in a vintagey industrial kind of way. Just thought it would look nicer/ cleaner to have something on the floors. What about vinyl or tile?

Moisture mitigation is when a basement specialist comes in and shot blasts the concrete to rough it up. The sprays/rolls two coats of water proof sealant onto the rough concrete. Then tops the rough (yet sealed) concrete with more concrete. Thereby covering up the mitigation. If you want a "painted" finish (or epoxy), the concrete company can throw down a HIGH END concrete topping (at your expense of course) it can be polished up/sealed as the "finished" floor. At that point, it will look SOOOOO GOOD you would cry if someone were to cover it up with paint.

As for vinyl, your concrete must be flat. To repair damp concrete, you need moisture mitigation ($5/sf see above. A tile install would have to have special application because of the high moisture content in the concrete = moisture mitigation for $5/sf (see above).

As you can see, damp concrete REALLY puts a damper on most people's finishing budget. The moisture mitigation needs to be done for anything other than carpet....mainly because all rigid floors require "flat". Old damp basements normally have wonky, wavy concrete that needs work to get it to "flat".

It will come down to budget. Do you have $5/sf extra to get the moisture mitigation done?

thx-good info - yeah I do think it would be worth it - at some point later on, once I get other things out of the way. Its "just a basement," and will never be "finished"in the sense of having walls and actual rooms ...but no reason it still cant be pleasant, clean, useable space for working on stuff.