Why do my Cacti bandwidth graphs seem to be backwards (i.e. inbound traffic shows as outbound and vice versa)?
The graphs are plotted from the point of view of the host machine where each VPS has a network interface going to it. Therefore traffic going to your server is going out from the host, and data coming from your server is coming in to the host. Just reverse the directions if you want to think about from the point of view of your own server.