As long as you never let your gear unattended (or dress like an obvious tourist), I think you're safe. This is something I wrote in another thread about Buenos Aires some time ago. I hope you find it useful:
be careful about street shooting in buenos aires. nobody will care about you and no one will confront you like in the USA. on the contrary, most people smile while looking at the camera or just look away (they will just know you're a tourist, they're used to it). that's a nice thing about street photography here.
however, as everyone knows you're a tourist, everyone will know you're an easy target. in downtown always wear your camera and bag bandolero style (or wrap the strap around your hand or wrist) and always have it closed and on your side/front, never resting on your back. some people on bikes and motorcycles can steal your cell phone/camera/bag while riding and take off so fast you'll never see it again. i've seen this many times.
robberies and pickpockets are common in buenos aires. it happened to me and my girlfriend one night while walking on a very crowded street that attracts many tourists (florida st); after walking for a while her cell phone had been stolen and we didn't even notice.
just be aware of your equipment, never leave it unattended, and you'll be fine. check out this link from the US embassy for more info:
http://travel.state.gov/travel/cis_pa_tw/cis/cis_1130.html
from that link:
A common scam is to spray mustard or a similar substance on the tourist from a distance. A pickpocket will then approach the tourist offering to help clean the stain, and while doing so, he or an accomplice robs the victim. Thieves regularly nab unattended purses, backpacks, laptops and luggage and criminals will often distract visitors for a few seconds to steal valuables. While most American victims are not physically injured when robbed, criminals typically do not hesitate to use force when they encounter resistance. Visitors are advised to immediately hand over all cash and valuables if confronted. Thieves will target visitors wearing expensive watches or jewelry.
this has happened to me as well. being asian, they thought i was a tourist but i immediately knew something was wrong and refused to get their help. it's quite funny cause a week later i got an email from the us embassy with this information (i'm a US citizen)...
having all this in mind... buenos aires is great for black and white street photography, and people are usually very nice and willing to help. oh and the food... i'd spend the rest of my life here just for the food. be sure to go to a restaurant and have a "parrillada" or "asado" and you'll know what i mean
😉 the cheapest meat you can buy here is better than the most expensive meat you get in korea or USA (in my experience).
check out my site for some pics in the city.
http://www.mumuki.com
a typical scene in downtown buenos aires. some guys having lunch and a protest behind them. i'm going to california in june and i'm worried about street photography there... i'll miss this city's craziness.