I plan to do some more work soon to determine how 'insolvent' (though thats a weird term to apply to a sovereign nation) the Brazilian government is. Here are some quick figures I gathered recently (they might be off by a little bit)
Domestic BRL debt converted to USD $670B - at 14-15% annual interest
USD debt $30B - at 4-5% interest cost or so
Petrobras USD debt $100B (not explicitly guaranteed by the government)
BBras and Caixa USD debt about $70-$80B (not explicitly guaranteed by the government)
Thats roughly $900B USD at pretty darn high interest costs. Meanwhile the FX reserves are $375B, that pays 2-3% a year.
Interest payments are about 5-6% of GDP (I believe that is net, that is, after the income from reserves), total fiscal deficit is about 8-9% of GDP (the difference is the primary deficit). GDP is $2.2T USD
At this point, the government no longer runs the country. The market does, if people think things are going to be alright, they will be. If they don't, they won't. Commodities are also a factor too. If oil goes to $20 and stays there, Brazil will need a IMF bailout or it will default (or maybe they will just print money), if it goes back to $80 along with the commodity indexes, then Brazil is a huge buy.
That's what makes it tough. You got to predict how people will percive the situation and where commodities are going. But a lot of the times you can make bets directly instead of using a proxy.
I do think the Petrobras corporate bonds are a dangerous play. If there is one debt they might not stand behind, its that one. With the state banks I don't think they will have much choice but to bail them out (although, I don't think they are in any financial trouble as of right now) otherwise you just have a massive bank run and a depression