I think that character flaws like swearing help not hurt evangelization because who's attracted to someone who's perfect? They say, if I can't be perfect like Terabitten, what's the point. But if they can say, it even works for a foul-mouthed old barstad like Terabitten, maybe there's a chance for me, then God's got someone He can work with. He knows what He's doing.
No one is perfect. Trying to aim for it is hopeless, but perhaps admirable. Trying to pretend to be is ... Well you make up your own mind.