This page of the Saints Row guide describes side activities from the Side Hustles category available in the Mercado district. Each of them has its own goals that must be met to receive the reward.
Reward: Depends on the rating.
Starting the quest: Talking to the woman in the western part of Mercado unlocks the remaining @tcha side activities available on the map.
The first task of this category can be found in the north-eastern part of the district, after the first conversation. Your mission is to go to the place and rate it. The lower the rating, the more opponents and the better the reward. You just need to protect your rating by eliminating the enemies and survivng. Afterwards, you will be rewarded with money and XP.