Jamieson, Fausset and Brown on 2 Peter 2:17

17. (Jude 12, 13.)

wells--"clouds" in Jude; both promising (compare 2Pe 2:19) water, but yielding none; so their "great swelling words" are found on trial to be but "vanity" (2Pe 2:18).

clouds--The oldest manuscripts and versions read, "mists," dark, and not transparent and bright as "clouds" often are, whence the latter term is applied sometimes to the saints; fit emblem of the children of darkness. "Clouds" is a transcriber's correction from Jude 12, where it is appropriate, "clouds ... without water" (promising what they do not perform); but not here, "mists driven along by a tempest."

mist--blackness; "the chilling horror accompanying darkness" [Bengel].