While I haven't heard of the rule the premise makes sense, though it may actually end up being misleading.
If Bangladesh makes the news, it's usually because of another catastrophic flooding due to monsoon rains. Being an impoverished country with no great influence on world events, very little attention is paid to local politics etc.
If a reporter in Europe or the US is told to report on something in Bangladesh, it's likely they know nothing about the place, not even stereotypes. All they have to go on are the facts, so they'll stick to the facts, or look it up on official country information databases.
As you get a little closer, reporters will know more urban myths and stereotypes about familiar countries, reducing the accuracy of their 'anecdotes'.
Get even closer, and knowledge will increase in accuracy, but the reporters' own agendas will start skewing things, because they are more involved in the outcome.
What's misleading is the fact that Bangladesh makes a uniquely good example for this rule (being distant and unknown), but many other countries violate it. Iraq is further away for the US, but reporting from there is nothing near as factual as the reporting from Bangladesh.
With the advent of the internet, I don't expect this rule is valid anymore, as it's not distance but amount of media attention that determines how much people "know" about some place.