Recently bought a house and sewer smell is coming out of floor drain. Any cheap fix you guys can recommend?

Has it been dry a while? Pour a bunch of water in it and see if the smell goes away. Once the P trap is full of water it will block the gas coming up the drain.

I have to do this with my tub every once in a while since I have a standalone shower and I only use the tub a couple times a year at most.

This is the answer. If it’s a drain that you don’t use often, once you run water through you can pour a little mineral oil in to prevent evaporation over time.

try dumping water down it. If the house has been empty for a while, the water in the trap may have just evaporated (thus allowing stinky stinky to rise)

This is the right answer. The P-trap (named for the shape, not the substance) dries out and let's gasses pass. If you are feeling extra about it, you can add a capful of bleach the first time to sterilize the inside.
- This is literally why The U-trap was invented.
I don't think it has P trap. I tried pouring in some water the daybi moved in but that didn't help
- Takes a bit. A cup won't do it, try a bucket.

Borax and boiling (near) water

There's no P trap
- Oh, yeah that would be bad

Try flushing every drain point, sinks, showers, Laundry, toilets, outside, with a heap of water, and chemicals to if it will make you feel better, Drano worked for me in my old place.

I think there's no P trap installed so no point of pouring in water and chemical.
- Unless someone has built it super dodgy there most certainly would be one, if not near the inlet of the drain then certainly before the sewer big old cast iron thing, probably underground, if you live in town. if you're brought an old farm house that old mate built himself then lord only knows

I would have suggested cloudy ammonia but you've already poured bleach down there. Not a good idea now.

Pouring anything down there will not help because I think there's no P trap installed.
- Can always pop the grate and see if there's a curve

Yes. Pour hot soapy water down that and any other drains near it. The trap has dried out.

I don't think it has P trap installed. I already tried water , bleach etc but the smell is still there.
- Floors drains are required to have traps so there’s something else that drains into that would be the culprit. I knew someone else with this problem and discovered the hot water service overflow tray was actually plumbed up to drain into the laundry floor drain. The trap had dried out on the overflow tray and was causing the floor drain to smell as well.

If you don’t have a P-trap in your floor drain, the correct thing to do is add one.
If you’d like to avoid that, there are devices made that claim to keep out sewer gasses from floor drains. I’ve not used them, so I can’t say how well they do/don’t work. I searched for “floor drain check valve”.

I don't know if its the drain or the smell is coming from back of the toilet. Its a shitty american toilet with skirts that covers everything to make it look fancy. Fuck I hate anything made that's made in america.

Have you tried shooting it with a gun?

It's a house not a school