Ironically, MTV saved their career. Videos were supposed to kill off the ugly rock dinosaurs and lift the beautiful. ZZ Top knew this and commenced with the most successful reinventions of a public image ever. They should have died; instead, MTV practically killed supposed rock sex symbol Billy Squire, his "Rock Me Tonite" video being considered one of the worst ever.
(Squire lived on though with sample royalties from hip-hop artists. But his video dancing was all his. Just look at his video for "The Stroke"; his style could be considered a form of juggling.)