You get what you pay for! If you go to the upscale supermarkets, the quality is good. If you go to the "popular" supermarkets and open air fairs in certain neighborhoods you'll find a level of quality that ranges from "just acceptable" to very bad. This has been my experience and I am the shopper in our household. 

SP capital? Go to a feira, they're fantastic.

OMG! Guys come on! Really? I grew up in ES and MG, now I am in the U.S. I know for sure that the fruits in Brasil are awesome! Can't say anything about SP, but it sounds like what I use to hear in Brasil when I was a child that the best coffee is sent to other countries and we had the worse kind...since we are from small town we get it from the people who grow it.

i am mixed on this.  the feiras here (CTBA) are expensive, and the more expensive markets have mediocre produce.  I get the best produce though at the sacolaos or semi-wholesalers that are ubiquitous here.  When in SP, I get fantastic quality food at the feiras.  In both places, the "povao" markets often have good produce at fantastic prices but you need to know what's in season and how to choose well.  We also have some local fruit and veg shops that have amazing and in some cases organic produce, good prices and fantastic taste.  Definitely not the "fruit boutique" kind of stores, much more humilde.
I should say that most of my friends, Brazilian or otherwise, don't know the places I frequent, and I find myself bringing people with me all the time.  I guess I have a nose for food and bargains.

Bigoro's right on with the coffee, though... it seems with coffee, beans and rice you get what you pay for.  Don't buy the cheap brands or you'll be sorry.  We also get beans and coffee from local producers and they're fantastic.  Not sure if the best are going overseas, but the coffee we get from family members in north Paraná goes to Cafe Damasco if we don't get it.