Just had to solidify my point, haha.
But seriously it is an important rule of thumb for vintage pennant collectors...
Be extremely cautious when considering a generic pennant purchase. Really do your homework, and let logic prevail over wishful thinking. I know that we (as collectors) automatically identify pennants with Baseball, or with Sports in general. But they were also quite popular at other non-sporting events back in the day.
If I saw an image of a generic pennant in a vintage photo, being waved in the stands, I'd feel comfortable buying it. But anything less is a big leap of faith, without proper or convincing provenance.