The key question is whether the question resolves around a point that is something that would matter to someone doing travel. (That is, would someone alter their plans or change their actions if they knew the answer.)
There's a whole subsection of the tourist industry called "Ethical Tourism" - For many people it isn't simply enough to drop into a country, gawk at the locals, and fly out without thinking about how you, a foreign interloper, have affected the place you visited. Instead, people want to make sure that they aren't exploiting the locals (and the local environment) by their actions - or even to make sure that their visit has improved the place they're visiting.
So I disagree with an assertion that questions about "where the money goes" would be off topic, categorically, or that "behind the scenes" corruption that the traveler isn't directly participating is off topic.
General questions like "Is there corruption that affects the locals?" probably wouldn't be on topic, as it's about the locals and not travelers, but questions like "I hear there's a lot of corruption: is the entry fee to this national park going toward conservation efforts, like they say, or is it mostly lining the pockets of local bureaucrats?" would be.
The key difference is that the answer to the latter would (potentially) change your actions as a tourist. If the national park fees go to corruption rather than conservation, you may decide to go to a private game reserve which does devote their money to conservation. Or you may decide that you'll skip the park (or the trip) altogether, rather than support a system with corruption.
TL;DR: Asking if corruption exists, in a general fashion, is likely off-topic, but asking a question about how corruption affects a traveler is on topic - even if it's just a moral consideration.