In Scarface right after making the deal with Omar Suarez, Tony says he explicitly doesn't like Colombians but the reason is never shown in the movie. What is it?
In the late 70s early 80s, the colombians cut off the cubans from the cocaine smuggling trade. Cuba was the "middle man" and when the colombians decided to keep all the profit, that's when the drug wars began.
I hope this answer from Yahoo will help you to understand Tony's hate for Colombians. Besides that Tony is considered that they are not good for business, probably referring to the brutal methods by which Colombian cartels are known.