How common are dishonest buyers and sellers in real-estate?

[Account Closed]

Was reading this eye opening thread here....

https://www.biggerpockets.com/forums/223/topics/39...

and one common occurrence for this guy was finding many dishonest buyers and sellers.  Is this really that common?  I assume places in Canada, like Ontario, British Columbia, Winnipeg, etc, aren't excluded from this?

Do you guys have a methods or tricks that can determine if a buyer or seller is dishonest?  Like the first 5-60 minutes of meeting them?  First couple of questions to ask?  

Thanks in advance!