A lack of filter means saying whatever is on your mind without considering politeness, appropriateness, relevance, or respect for the situation. People who have no filter may use profanity when they should not or bring up sensitive topics such as religion, politics, sex, body parts, or body odors in ways that offend others. Human communication follows social norms, and these norms discourage creating unnecessary controversy, embarrassing people, or discussing highly divisive topics in casual conversation. When someone ignores these norms, they may be seen as awkward, weird, or socially unaware, and others may feel unsafe or uncomfortable interacting with them. Appropriateness is a skill that can be learned by thinking before speaking, considering the audience and situation, and asking whether something is respectful, relevant, and suitable to say.
I’ve always had an excessive filter pipeline that slowed me down. My partner always had no filter. It was like Katara with Toph (but easier than Toph, much much kinder and well meaning). After years we both somewhat met in the middle.
Let’s put it another way: I needed alcohol to shut those inhibitory filters down; she did not lol.