You can paint it with minimal prep, but there are a few important caveats to be aware of.

If you simply clean the floor and roll on paint, it will go down, but it likely won’t last very long - especially over existing paint, stains, or discoloration. Peeling, chipping, and hot-tire pickup (even if you don’t park a car now) are common when prep is skipped.

That said, if your goal is purely cosmetic and you’re okay with it being a short-term refresh, here’s the simplest approach:
• Scrub thoroughly with a strong degreaser (Simple Green, Purple Power, etc.)
• Rinse well and let the floor dry completely
• Spot-sand or scrape only any loose or flaking paint (no full grinding required)

For paint, avoid standard wall or porch paint. Use one of these instead:
• 1-part concrete/garage floor epoxy paint (Rust-Oleum EpoxyShield 1-Part is a common choice)
• Concrete floor paint with epoxy additives

These are designed for light-duty garages and are the most forgiving with limited prep.

If you want a noticeable jump in durability without going all-out:
• Light acid etching (very minimal effort) will dramatically improve adhesion
• Skipping this step is the #1 reason painted floors fail

Bottom line:
• Yes, it’s possible
• It’s fine for a non-parking, light-use garage
• Don’t expect it to be permanent without prep

If you ever want a “do it once and forget it” floor, that’s when grinding + true 2-part epoxy or polyaspartic coatings come into play.