Avis marketing VS Avis front-line operations, I've been discovering, are two very different beasts. I assume they are always trying to find a way to nickle-and-dime me once they get my business, so, whenever possible, try to protect myself.
Example 1: I approach any customer goodwill gesture with suspicion now. Verbalizing my AvisFirst status then offering a nicer car, does not mean the nicer car comes complimentary.
Example 2: An agent verbally saying a "few dings on the bumper are no big deal" holds little value when the return agent feels otherwise. It needs to be documented.