I went to Ciudad Perdida with Magic Tours and it was a pleasant trip, so I had no qualms booking a 2 day tour to Cabo de la Vela from Santa Marta with Magic Tours.
After traveling in more than 60 countries I can confidently say that this was one of the worst travel experiences of my life, and I felt much like a refugee or prisoner of war during these two days of hell.
Cabo de la Vela is in an extremely poor and dirty part of Colombia. The Cabo itself is a bit of dry dusty hill. The beaches are filthy, with overflowing / tipped over trash cans in the car parks. You need to pick your way through copious plastic rubbish on the paths to the beaches, and there is nowhere clean to sit on the beach because there is so much rubbish. There are thousands of prettier coastal landscapes and thousands of nicer / cleaner beaches in the Caribbean, let alone the world.
If you have EVER seen a dry landscape before, if you have EVER seen a beach before, if you have EVER seen a dirt road before, if you have EVER seen people living in poverty before, then there is absolutely no reason to come here.
The "sights" we saw along the way I would not even count as sights. Our driver / guide did not stick in any way to the timetable, instead, he treated the trip as if it was his holiday, and we were tagging along. Thus we visited the salt pools in Manaure (you get to gawk at some of the poorest men in Colombia slaving away in appalling conditions), we stopped in Uribia (a town notable only for being even more full of rubbish that its surrounds) for the driver to buy contraband gasoline from Venezuela, we stopped to look at some modern wind turbines (which you can find in just about every country these days ie NOT a tourist attraction). We sat around for more than an hour waiting for "lunch" (at 5pm, and after that the guide announced that since we had eaten so late, we didn't need to have dinner!) and arrived at Cabo de la Vela in time to watch the sun set (again, if you have EVER seen a sunset...)
The accommodation - not "Rancheria Wayuu" as advertised, but a squalid place called Donde Mamicha - was horrifying. Hammocks were hung for us in the restaurant next to some boys watching tv - ie no privacy, no blankets or mosquito nets, and THERE WAS NO ACCESS TO FRESH WATER. There was a huge bucket of rancid sea water next to the toilets, and with this we were expected to make do. Of course, when the guide had swum in the sea the next day and wanted to have a bath himself, HE managed to get himself some fresh water to wash himself.
The next day we were held captive by the guide on a hot a dirty beach for some hours and taken to a filthy fly blown restaurant for lunch. Unsurprisingly, I contracted a parasitic intestinal infection requiring drug treatment. Despite continuous travels in often poor countries - this was the first time this had happened to me for 5 years - a good indication of how filthy Cabo de la Vela is. I cannot overemphasize how unpleasant these couple of days were, and would not subject my dog to such a trip.