Each person and situation is key but, here are some examples and take it from here.

Mortgage Brokers, I am very cautions of fees paid out.  On smaller deals, they get paid from the bank - not me.  if they show up to your meeting in a new BMW and a designer suite and a $500 bag, how much are they charging you.  Tell them you do not sign any false documents.

Real Estate Agents. 

Investors:  Where did the money come from?  We know one person who paid a mortgage broker a good sum of cash to pay off people at the bank level to look the other way to apply for two lines of credit.  When asked why he did it "my mortgage broker said I would be fine .  No this person is out looking to give the money away to an investor.  Should our example man get in trouble with his fraudulent LOC application, I may have all of my properties investigated since the one I did with him may be part of this feculent behaviour.  As a result, i am quickly distancing myself from him.