A hot-tempered roofer and his baked teenage apprentice climb the ladder of the trade world and swindle their way to success.

Agreed with the above.

Also, is there a way to make this pair more empathetic? That's not to say that the main characters have to be "good" people, but being hot-tempered, stoned, and evidently greedy, aren't qualities that alone give an audience much to hang their hat on. Could they at least have a noble cause motivating them?

In the case of this logline, I think you need to add a bad guy, or something that is standing in the lead character's way.

Also, you are describing "Life as normal" for these characters. A story usually begins when something interrupts the Norm.

As mikepedley85.

And what's so funny about swindling innocent people?