I've been asked to explain why people say вешать лапшу на уши for uncovering lies and expressing distrust. Where does it come from?
If I understand you correctly, you mean the Russian expression вешать лапшу на уши - "to tell lies, to give baloney to somebody".
As far as I can see, there are two things to be explained. First is why the verb is вешать - to hang. Second is why the word is лапша - noodles.
Internet search shows that the etymology of this phrase is unclear, and there are several versions.
Лапша stands not for "noodles", but for "long and narrow rags of cloth", вешать лапшу means "to hang rags on somebody's ears", that is, to cover or to knot the ears so that the person cannot hear clearly.
Лапша comes from criminal argot and means case, "to hang a case to somebody's ears" originally meant "to set up someone". However, it doesn't actually fit the meaning of the expression as we know it now (see above).
Finally, лапша simply means "noodles", but the expression got naturalized because there is a verb облапошить that sounds similar and means "to cheat, to trick someone" (usually by a very easy trick or because this someone is a duffer). Вешать is probably used because of another expression развесить уши - "to listen without thinking critically", literally "to hang out ears".
None of the versions is reliable. I personally prefer the third one.
The meaning is so because one cannot see the noodles on one's ears. One with noodles on the ears would seem funny to the surrounding people but he himself would not notice anything.