Take another look at the original sentence:
You wanted to fix it this way:
A comma splice occurs when you have two complete sentences joined with just a comma. No foot powder, no shoe insert, no expensive soap can kill the odor of Bartholomew's feet is one sentence. When he takes off his shoes, even the goldfish gag is the second sentence. A conjunctive adverb like thus does nothing to alter the fact that you have two complete sentences connected with a comma alone.
You might want to consult the rules for fixing comma splices and fused sentences.