To me, there is a difference between graffiti and street art. Street art goes above and beyond graffiti, and is a pleasure to look at. There is a LOT of street art in Buenos Aires, and some truly amazing street art in San Telmo. It is easy to just walk up and down the streets of San Telmo, and check out the buildings, and news stands.
If you are up for it, there are guided tours as well. Here are two that I know of: