The following situation is both hypothetical and rhetorical, so pay it no credence except to submit advice.

Say in your professional life you're a stock broker. One of the companies you deal with makes sweaters, that are designed to coordinate with a line of neckties that they do not produce. Your contact at this company sends you a necktie. Not to curry favor or as any form of payment, but because he's the kind of guy who sends out neckties. Now, this necktie wasn't even made by the guy who sent it to you; they just have them because they're tangentially related to what the guy does. You don't look good in this necktie. Is it morally wrong to take the necktie, which is perfectly resellable, to a department store and trade it in for something you actually like? The deparment store gets merchandise, you get something, and the guy had nothing to gain or lose by sending you the necktie in the first place. What do you think?