Oh man I like the mental image of this a lot. Geto lounging around Alciel's small, cheap apartment, sipping tea (that he brought himself) and bitching about work while Alciel hand sews some alteration or another.

And yeah, Alciel is both way to sharp to miss anything about what's he's asked to clean up, and way too reliant on this small cash-only income stream to ever want to endanger it (no matter how much he complains). No paper trail, no evidence, no questions, and no need to declare it as taxable income.