It's not always possible to say definitely is some text was AI-generated or not, but one sign that it is very likely AI is a kind of blandness of affect. Even marketing text carefully written by humans to avoid offensiveness tends to exude a kind of breathless enthusiasm for whatever it's selling. If marketing text is oatmeal with raisins, AI text is plain oatmeal.

It's possible to adjust the output of an LLM with temperature settings, but it's just fiddling with a knob that only vaguely maps to some control.