How to respond a Colombian street vendor

One thing you will encounter in Colombia are the many street vendors. Many of them really are disguised beggars. This is revealed by the word "colabórame", which means "cooperate with me".
Now, if you don't want to buy the product, there is an easy way to get them to understand this, and that is by saying "Gracias". Don't say "No, gracias", because in Colombia negative messages are considered rude.
If the salesman is a polite person, which many of them are [it doesn't hurt sales], he will respond "Dios le bendiga" (God bless you) and go on to the next customer.
If you accompany your phrase with a short smile, then look away like you are busy, the message gets even clearer. Sometimes this will need to be repeated a few times, but eventually the seller will accept the fact without feeling offended.