 However, many authorities readily admit that they do not have the manpower to enforce laws and regulations in large, crowded and numerous tianguis, although raids are performed sporadically, especially looking for stolen and counterfeit merchandise.Stolen merchandise, especially electronics, and unauthorized CDs and DVDs is the largest criminal activity found in tianguis, with copying of CDs and DVDS one of the most lucrative businesses.Tianguis sellers can be quite sophisticated.