I'll preface this by noting that the sin of sloth has traditionally been understood to be a sin of omission, not just commission, i.e., you are insufficiently devoted to the things you ought to be.

Which means you could, in theory, have a (reflavored tiefling) devil paladin so devoted to sloth he works against evil causes. He's not interested in good per se, it's just that advancing the interests of good and traveling with a good adventuring party has the best ROI for failing to carry out his evil responsibilities.

Naturally, this has caused a fair amount of controversy among sloth devils, and there is a multi-century trial going on in the Hells about whether this ought to be allowed. This is not expected to be resolved in the foreseeable future because the advocates for both parties keep filing their responses well after petition deadlines expire.