Smarts rhymes with:
k-mart's, mart's, marts, martz, art's, arts, artz, bart's, barts, bartz, carts, charts, dart's, darts, departs, descartes's, hart's, harts, hartz, heart's, hearts, imparts, k-mart's, kartes, mart's, marts, martz, part's, parts, parts', schartz, spartz, starts, tarts, upstarts
Smarts sounds like:
schmertz, smartass, smarties, smartish, snorts