Well, you sort of have me at a disadvantage.  I haven't watched TV in nearly three decades, and have devoted almost no time paying attention to Al Sharpton.  I neither know nor care whether he owes taxes--between him and the IRS.  Give unto Ceaser and all that...

As for "Imams" (proper term "Qtib"), the ones I know subsist off saadaqa and khums from the believers--and the best ones (i.e the Sayiidin) distribute most of what they receive to those who need it more than them.  What clerics of other faiths do, I don't know.