I've always liked Panchitas #2 for a $3 lunch. For that amount, you get two pupusas of your choice and a bowl of slaw. Not bad if you're in the Mission but aren't in the mood for a taco or burrito. Not the best pupusa in the world, but huge, cheap, and serviceable.
I took BF last night for dinner. I ordered my usual 2 pupusas, which were fine. He ordered a deep fried tilapia and a horchata. Wow. We should have left the minute we tasted the horchata. It tasted like the inside of a dirty refrigerator. I think the ice cubes were frozen in the same freezer as rotting meat. The horchata itself had also absorbed a lot of fridge odors, and was kind of thick and sugary to boot. Terrible.
The tilapia had clearly been frozen, and tasted muddy with an off texture. We usually love tilapia, even the ones that are sold on ice in Chinatown (already dead). This one tasted like it had been frozen for ages. Maybe the ice cubes were made in the same freezer that this tilapia came out of. BF put it on his list of top 5 worst dining experiences ever. I was ashamed.
So if you do find yourself inside Panchitas #2, do yourself a favor and stick to the pupusas and buy a canned soda or a beer.