renting space of old hair salon

I'm renting a small store that was a hair salon. I have noticed sewer smell in the bathroom (I know, haha). They had a washer/dryer set up in there. Now, all the hoses and pipe have been left open. I keep telling my husband (I know, he's not the handy type, haha), that the fumes are coming from there. I hate to say, but the landlord wants to do as little as possible, and I just want to know what I am talking about before I approach him about it. If its as simple as sticking a rag in the drain pipe and capping the hoses, I'm sure I could manage that.
Thanks for any advice.

If the trap on the laundry standpipe isn't getting refilled with water by the laundry machine, then the trap will dry out from evaporation. This will allow sewer gas to get into the building. If this is the case, the drain needs to be capped off in a more permanent manner than a rag or pouring water down it.

Thank you. Now I can tell the landlord with confidence that it needs to be fixed.