Colors and smells
The market in Oaxaca in the state of the same name, has the unique distinction of being the first market on your trip from Mexico City to Chiapas where you find Mayan culture. The characteristics, the products...everything is so different from colonial-style Puebla or the coastal cities. The most popular treat in the Oaxaca market are "chapulines," red roasted crickets in a plastic bag, seasoned with salt, lemon, and a pinch of spice.
Another regional product is red chili peppers which are sold dried and are part of some of the region's more spicy dishes. The market itself is the same since the 17th century. The market actually reminds me a lot of ones I saw in Guatemala, both in the look and way of speaking: "what're you having," "we've got chapulines," there's tequila," "chilis over here"...the same rhythm throughout the entire market.