When is a scoff fair enough?

Now that's a lotta 'f' sounds. But seriously, we need some input here.

Apparently because the fan in our office is an oscillating fan, it's going to oscillate some air when it's switched on. I scoffed at this notion but not because I doubt it. No, because I found my colleague's choice of words rather scoffworthy... Even amusing!

Now I leave you with some timeless questions:

1. When is an oscillating fan not an oscillating fan?

2. When is a scoff fair enough?