Any lie is bad, no matter how small as there are no ways to predict how "small" it will stay, or what else it will affect in your life and the life's of others.
One is certain, any lie will cause something bad, some immediately, some later in time, but it will always happen, no matter how much you will try to avoid the consequences.
Its so bad that it might stretch its negative echo through generations..
In short, don't let them get inside your life in a first place, never.
If you see any lie is getting in your life from the outside => clear it.
There is only one situation I could imagine where a temporary lie would make sense, its when a lie can save a life, or multiple life's. But even in this case one should clear it as soon as only possible.
Make sure others can't lie to you too, no matter which from which position, relation or for which reason.