have you ever known someone who seems to not really understand what they're saying when they talk

not like people who are ignorant or stupid, per se, but who just seem to be saying whatever random shit floats into their head as if they're just automatically responding to stimulus without actually trying to say anything

because i think my friend does this and i don't know whether or not it's justified to be frustrated/annoyed at some of the stuff they've said i suspect was just mindless spew