There's no denying that you have to be more safety conscious travelling around Central America, as opposed to westernised first world countries. For the most part, the only real danger and annoyances will be getting gringo-taxed on products/services.
These countries, apart from Costa Rica, have a real problem with disposing of waste; you'll often see trash burning at the side of houses or piles of it thrown along roads. Unfortunately, this problem also extends to several of the tropical Caribbean islands.
For over landers in their own vehicle, the manic and reckless driving of locals can be a scary prospect. We found the worst drivers to be in Mexico and coincidently the roads (in particular in the north and west) were dangerous in themselves, with potholes and topes (speed bumps), narrow roads, wandering animals and children running around (as we found out the hard way). We found the majority of drivers were rude, inconsiderate, keeping their full beams on at night and driving extremely fast for the conditions. Even though we did do half the driving in the evening and night, we would recommend to try and avoid doing this. It's not worth it, as you'll see by the constant reminders in the death memorials scattered along the roads.
The police did try to bribe us a lot throughout Central America, but surprisingly we never actually paid one bribe. Everyone we met travelling in his or her own vehicle had paid at least one bribe. We just managed to swindle out of it. Again, we found Mexico to be the worst for this. The police are often the problem, not the solution. We found that playing the 'I don't understand' card worked in our favour, and they would give up asking eventually. Do NOT give your actual driving licence or documents to the police as they'll use this as a mechanism for bribing. Take lots of photocopies.
In relation to other dangers, apart from a phone (which was my fault as I left it on the side of the car whilst we were fixing it), we never got anything robbed from us. However, we did meet many people who had had things stolen. There seemed to be a common theme though - they were often alone at night or drinking or in an unlit notoriously unsafe area. Don't carry your full wallet around with you if it isn't needed. Someone did attempt to rob us at knife point in Granada, Nicaragua, which was surprising given it was a nice city with a lot of ex-pats and tourists. Luckily, we didn't have anything on us, but as you'll see from the blog and pictures Gwyn got injured. Fortunately, it was nothing more serious than the marks on his back (albeit they looked awful), but it still massively shook us up. Please don't make the same mistake as us. Avoid malecons (water fronts) at night.
Other annoyances included the vulgar behaviour of men towards women, which ranged from hand gestures to graphic language. Just ignore it, as it's really not worth the hassle.
Finally, the Latin American people all have the same very irritating and often very loud car alarm. We knew the sequence after a week of being there. You'll know exactly what we are talking about as soon as you go.
Just use your common sense and all should be good. Don't let the horror stories deter you from these countries. It's very embellished and most of the time we felt very safe.