There are examples in Torah thought that prayers can and cannot reach Hashem. For example, the idea that there are 955 heavens and our prayers can only be carried to the 900th, and we are responsible for making sure they climb the final 55, or the aggadic idea I once heard that one's prayers don't reach Hashem when one has touched a dog. The ideas that the gates of tears are never closed (Berachot 32b). I am not looking for a strictly theological/philosophical/logical solution to this seeming paradox, or to attain a comprehensive understanding of the topic in general or anything, I'm sure that has been asked and dealt with here before.
I am simply looking for well sourced mashalim in helping understand it, on a more intuitive level. For example, it might sound like this:
[Completely made up example] Prayer that reaches Hashem is, l'mashal, when a husband is hearing a message from his wife who he hasn't seen in a year, paying full attention and being very moved, whereas prayers that 'don't reach Hashem' are more akin to a husband who is listening to his wife at a time when he is very busy and distracted l'havdil
Do we have any mashalim? Whether it be Talmudic, Rishonic, from a piyyut or a maggid or chassidishe maaseh, I would love to hear any mashalim you have heard on this concept! I do understand that the whole idea is a "mashal", but hopefully you know what I mean - sometimes it takes more mashalim to help understand a deep mashal!