Failure to Respond to a Permission Request: What Does it Mean?

Dear Rich:  In a recent post, you made the comment that it’s inefficient for large companies to deal with and track minor permissions requests.  I’m curious about situations where a request is made but no response is given.  While I know a lack of an answer does not equal permission, does the lack of an answer do anything to strengthen the fair use argument?  In other words, would my ‘good faith effort’ in trying to seek permission  weigh in my favor if I resorted to a fair use argument? A related question, regardless of how the previous question is answered, is it appropriate to associate no response with a lack of care about the particular request, thereby indicating a lower risk of being pursued?  A failure to respond to a fair use request should not strengthen or weaken a fair use defense. For example, in the Pretty Woman case (in which rappers borrowed the first line of the Roy Orbison song), the music publisher had refused the permission request. Despite the refusal, the rappers went ahead with their plans, and the Supreme Court ultimately determined that it was a fair use. The reason why the copyright owner's response won't matter is that a fair use analysis happens after a court has determined that infringement has occurred. In other words, by the time a court looks at fair use, permission doesn't matter. 
Why seek permission? If permission is unnecessary for a fair use defense, why ask for it? First, acquiring permission bypasses the need for a legal dispute  (and the uncertainties and expenses associated with it). Second, seeking permission also demonstrates your good faith and may mitigate the damages assessed if your fair use defense fails and there is a negative decision against you.
Does a failure to respond to a permission request mean that there is a lower risk of being pursued. We doubt it. Although, as anecdotal evidence, we can offer this story: Our mom called a lawyer at a well-known movie company for permission for her nonprofit to use a licensed character in a presentation. His response, "You never made this call." In other words, having to say "no," would have obligated the attorney to follow up. 
FYI Dept. -- Silence doesn't mean legal assent. We remember getting letters from lawyers that would say things like, "A failure to respond shall confirm blah, blah, blah." But 99.9% of the time that's just not the case. Inaction, or silence rarely triggers any legal conclusion (either affirmative or negative). For example, there's a famous 19th-century English contract case in which a man offered to buy a horse and stated that unless he heard otherwise from the seller, “I consider the horse mine.” The British court ruled that his assumption didn’t create a contract; the other party’s acceptance had to be clearly expressed.