There much ado about like at Beebs after actress Thompson was, like, very upset by, like, words and such. This comment by a reader named Colin was very clever.
Comparing "like" to "um" and "ah" as a filler/thought pause is okay, but there's one major difference. The listener can easily filter out the "um" and "ah" because they have no meaning. But "like" does, so the listener has to process "like" in the sentence's context to determine if it's relevant or not. This hinders comprehension because it has to be done before the full sentence is known. "I smell like a rat" means what? I stink, or I suspect a double-cross? Compare that with "I smell um a rat". No double meaning there.