Many animals like jelly fish have bad reputations. If it matters - some of these bad reputations may be deserved but some may not. For example the assumption made by some for example – that bats are dubiously motivated denizens of the night that set-out with the sole intention of getting tangled-up in people's hair.

For some reason - you may attempt this assumption and choose to set-out on an honest attempt to convince someone who thought that bats served many beneficial functions and did not in fact get caught-up in people's hair – that they were mistaken.

However during this investigation and debate - you may not in fact find much evidence to support this generally expressed assumption that bats gets tangled-up in people's hair.

You may actually find that the firm evidence supporting the idea that bats do not get tangled-up in people's hair would strongly contradict the generally expressed assumptions that they do.

At this point - you could then set about trying to establish why – against the evidence - these unsupported assumptions are still so set in the minds of some?

Or at this point – you could always say (as many do) that it did not matter very much. However, having already expended a lot of effort – this course of action at this stage may appear a little foolish

To choose at this point – against the evidence - to make yet another groundless assumption about the possible motivations of bats - may appear even more foolish.