Just kidding, there’s no secret to avoiding them, aside from not going to the beach. The top three things they’ll always say while slowly passing in front of you? Promoción (Promotion). Masaje (Massage). Cerveza (Beer). Other items you may see are shrimp, mango slices with salt and lime, articles of clothing and accessories. My guess is that if you want it, they’ll get it for you.
But seriously, how does one avoid them since they take the words “no, gracias” to mean “show me what your friend is selling”? If you are fair-skinned, there’s just no hope for you aside from staying in the water (although this isn’t full-proof as I’ve had beach vendors enter the water with their wares). On the other hand, if you could pass for the average Colombian though (wait, is there such a thing?), you might have a slight chance at some peace on the beach. The trick seems to be to barely shake your head side to side while making the universal ‘no-no’ sound with the tapping of your tongue on the roof of your mouth. Add a little shake of the index finger to it and it might be smooth bathing…at least for another minute or two.