Guest was irritated, and wrote review that the house had mold and 3 people were hospitalized. 

To irritate you. ;-)Actually it makes them feel good that they are now "connected" somehow.

Again, aside from the idea of water being wasted as a source of irritation for me, the raw cost of it from a business point of view is no matter, as long as you can roll it into appropriate rent.

They are out of Iceland and the barrier in language/verbiage was a constant source of irritation and problems.

Is it just the marketing that irritates these people?

(assuming they don't look to busy or come off as angry or irritable) I tell them I am interested in buying property in the area and then just chat for a minute and give them my card.

Assume it will happen, account for it in your math, and it will be a irritating situation instead of a devastating blow.And yes, when your rental (and lease options are really just rentals) is vacant you still have to make your payments.

I want to go in at 80% but my agent wants me to go in at 95%. secondly, i'm getting irritated at time wasted from going to many properties that have NO appeal to me.

The realtor seems irritated that we have to work with an FHA loan since I have to ask for up to 6% back in closing costs.

Unfortunately, it's a rehash and I think it's irritating as heck to have agents hawking shop worn properties and "new listings" .