CREDIBILITY FALLACIES.
Credibility fallacies are those in which uncertified people present themselves as experts: the famous actor dressed as a doctor recommending a certain medicine. The actor is not a trained professional and has no professional credibility.
FACT AND OPINION.
Certain keywords can be often be used to differentiate facts from opinions.
1. Generalizations. All inclusive or all exclusive terms that usually have exceptions: everyone, everything, no one, never, always:
It always rains in the summertime. (This does not take into account long droughts or geographic locations where rain rarely falls.)
Everyone drives a Ford.
2. Statements about the future:
We will never go there.