Oregon is even worst for Landlords and I would never invest here. 

This is also our worst tenant and we're counting down the days to get rid of her.    

Start, with the worst case scenario (can you survive it or what would hurt least) for both and then go from there.  

Let's also assume the room is always genuinely locked and I'll have a reasonable way to argue this, e.g. something beyond "it should have been locked".My thoughts:1) It's a locked door, literally no one will know there's a gym on the other side2) Worst case is that someone broke in, worked out or claimed to work out, and filed a lawsuit saying they used the home gym and injured themselfIf I have evidence the person broke into the room (e.g. video from the inside of them breaking the door/lock), would I still be realistically liable?

It could be true, but it’s just as likely there’s another reason the current owner is quite aware of, and you’ll find out the hard way if you buy it.By buying on could-be or pro-forma rents, you’re buying as if the seller had put in the work to raise the rents, without their actually having to do so.It’s a great deal for the seller if they can pull it off, much less so for you.In the best case scenario you’ve already paid top dollar and now have to work your tail off to “catch up” to your projections by raising rents as soon as possible (sometimes with negative consequences as you pointed out, Fan).In the worst case scenario you find out there was a reason rents were so low (e.g., significant deferred maintenance you hadn’t spotted on the inspection and that tenants were bugging the last owner about for years).

So the areas we buy typically have decent rental opportunities so worst case, we BRRRR

I do feel like waiting a few months wouldn't be the worst decision, but who knows.

Self help is the worst thing for landlord.

Obviously with the flu season looming I think I speak for a lot of landlords that another rent moratorium is probably our worst nightmare right now.

If it is a single family home, depending on its location, condition and how it shows it should sell pretty quickly so if they move out it wouldn't be the worst thing in the world, it might even make it easier to not have to worry about showing the property with tenants especially amid the current Covid situation.Best of luck!