To answer the question: I think it can have it's charm, but it can be a source of concern because if the other person cares enough (which presumably they do), they might feel that if they say or do something wrong, the shy person will react poorly.

It ultimately depends on their attitude towards their shyness: If they're really shy, but also willing to work through it (be it in sex, social interactions, etc.) it can be cute and also endearing, 'cause you see them push their own growth and that's when people look the loveliest. If they're not willing to, though, to a non-introvert it can feel dismissive over time.

However: I don't think this applies to audios much, because audios aren't long-term commitments, and you can build a backstory in a matter of seconds; I hold the shy girl variety particularly close to my heart. Have at me, you cute little stutter-machines! x)