I wouldn’t ever accept it. In my opinion, being untruthful is not an option. It’s a sign that he or she does not respect you and they couldn’t care less about being considerate of others.
I consider this toxic behavior, especially if they are constantly lying. You have to ask yourself, what are they up to? What do they expect to achieve?
Are they trying to manipulate you? Do they have a dark past that they don't want to share. This is okay unless you are in an intimate relationship, in which case people need to be open and honest with their spouse or lover.
There are exceptions however. A compulsive liar is definitely a toxic person, but you have to appreciate when someone simply feels threatened or intimidated. If you're not in a close relationship and you ask personal questions, for example, one has the right to not answer. If they are provoked, they may have no choice but to give a "white lie."