In first image the conditions of buying/selling are quite bad and the quality of products is not guaranteed.In all places from photos the customer is always right except first photo , there is no return or quality confirm.The safest products are in a brand shop as in 2nd photo and in shop as in 4th photo. All of these types of shops are in every city.What depends on me i don't think that street trading places are the best place to shop, i would better shop in a qualified market more expensive but sure that it is safer.