Oh, where do I start?
As a Brazilian, let me tell you right off the bat: we are the #1 procastinators of the world. Everything we do is only finished at the last minute, with half of the planned goals achieved and costing three times the budget.
It is highly questionable whether Rio has infrastructure to receive the Olympics. Not only our social numbers regarding violence and quality of transport have not improved, the lake/bay where many water games are supposed to be played have not been cleaned. These water are so polluted that they are mostly (and I mean mostly in "more than 50%") sewer. Trevor Noah from The Daily Show aired reports from some scientist who said that "accidentally drinking three spoons of that water is almost sure to make atheletes sic". I'm talking E. Coli here...
That doesn't mean the country can't host the Olympics. Under the hoods, a lot of extra money is being put into making this thing kind of work. But the process involves evicting families and police brutality towards the poor.
There are also two severe epidemics in Brazil right. The first is the Zika virus, which is primarily transmited by a mosquito (the Aedes aegyptis, same dude responsible dengue fever), and secondarily as an STD. This is not a very serious virus for adults or children, but there's enough evidence to link this virus to microcephalia -- in other words, women affected by Zika run serious risk of devliering malphormed babies (with small, disfunctional brains) up to two years after infections.
The second epidemics is in politics corruption. Our first female president is also our first female president accused of corruption. And her party is in deep, deep, uh, fecal matter. Right now Dilma Roussef is still the president, but she is excused from chair as an impeachment process is being run. Problem is: almost all politicians who are/were against Dilma are also involved in one or other case of corruption. Her vice president, who probably won't last much in the seat, is our interin president.
TL;DR: we are not even a month away from the Olympics and infrastructure is shit (literally, in case of water sports), we face serious violence/health issues, and we are not even sure who's going to be our president in the next months. So, yeah... there are lots of problems.
PS: pretty much no one is talking about Olympics in the streets right now.
