I'm a leftie, but fairly ambidextrous when I need to be.
I use my computer mouse right-handed (leaving the left one free), I knit right-handed and I smoke with either hand.
I have a left-handed bread knife, however. Try using a normal one with the blade slanted for righties in you left hand, and you'll see the problem.
The only hassle I ever got for it was from teachers. The one in nursery class ridiculed me in front of the whole class because I had trouble with shoelaces, and nicknamed me "helpless and hopeless".
Later on, a PE teacher made an drama out of me being the only one in class who needed a left-handed hockey stick.
And in music class, the teacher moaned that I had to lean over to do my work, because we had seats with exercise book rest attached to the arm - on the right hand side, of course.