I would accept anything that's not written by a single person. Well, technically everything is, but magazines and stuff have editors and are collective efforts to represent something more than just a single person's opinion. Thus, I wouldn't say a column would be enough, as those are generally specifically written as the opinions of a single person, but articles are supposed to be more objective and reflect the world better.
The other direction is when it seems very obvious, but if it's a deliberate stereotype, it's not exactly unfortunate*
, is it? It may be supposed to be offensive, parodic, funny, or just Values Dissonance
But really, the main point is that is shouldn't be enough that a troper found something he thought was an Unfortunate Implication
Of course, lampshades or other in-work mentions would be acceptable as well, as those aren't ambiguous at all.