So, Junk Fax Advertising is indeed against the law, but it is NOT against the law to send a fax to someone without prior dealings, or without their permission or without an "Opt out" clause.
Bollocks. It may not be against THAT law... but sending faxes with as benign an intent as annoying someone can be criminal. In NYS, for instance, you'd be violating the penal code.
Aggravated harassment in the second degree.
A person is guilty of aggravated harassment in the second degree when, with intent to harass, annoy, threaten or alarm another person, he or she:
1. Either (a) communicates with a person, anonymously or otherwise by telephone, or by telegraph, mail or any other form of written communication, in a manner likely to cause annoyance or alarm; or (b) causes a communication to be initiated by mechanical or electronic means or otherwise, with a person, anonymously or otherwise, by telephone, or by telegraph, mail or any other form of written communication, in a manner likely to cause annoyance or alarm; or
2. Makes a telephone call, whether or not a conversation ensues, with no purpose of legitimate communication; ....
Aggravated harassment in the second degree is a class A misdemeanor.
There may be a federal equivalent elsewhere in the law. Good rule of thumb: If it interferes with someone else, don't assume you're not violating any laws until you talk to a lawyer.
(And don't get hang up on that "how could they figure out my intent!" argument. Near every criminal locked up in the state had a jury of their peers infer their intent. [the exceptions being those who pled guilty])