An ambiguous or vague statement is always an acceptable premise. Common knowledge is a bad reason to accept a premise. Appeal to authority is a fallacy of relevance. Inductive arguments are always based on observations of the world. If an argument's premises are true, it must be a good argument.
Good analogies are always relevant.
An appeal to popularity has negative relevance. If a premise is relevant, it must be true. Inconsistent premises are not acceptable. Grounds and acceptability are independent of each other. A deductively valid argument meets the R and G conditions.