I've been in flea infestations and have a very bad reaction now when fleas show up.

Also, even if the seller eventually sees the escalator clause in the addendum, their initial emotional reaction to the offer is already biased.

@Bill Gulley gives some good advice.My reaction to the property you described was "that must be a rougher neighborhood". 

My gut reaction is to say no.

Likely a reaction from higher interest rates.I'm not seeing that in my target areas, but these trends may make their way over here soon (Scottsdale & Paradise Valley)

Same for all brokers.They absolutely refuse to participate with skin in the game, that's why the reactions to your questions have been overwhelming NO.

The problem is no one knows which species of mold any one person may have a reaction to. 

(from our core rental agreement)Mold may grow and exist in any structure where there is, or ever has been, a presence of moisture and a food source for mold to grow.Its presence may exist without the knowledge of the structure owner and may be concealed from the untrained observer.Some varieties of mold are toxic and may cause adverse reactions in certain individuals.Tenant and Landlord will complete a Mold and Moisture Hazards addendum that will become part of this rental agreement.MOISTURE AND MOLD.

His reaction, "I'm better off with a sure 18% percent return on my $150K.

I never really thought about it, until your reactions, but that to me has been part of the cash flow conversation.