for most it is considered bad form. I hate turning things around and for the most part I am ambedextrious (spelling?) Anyway, I use both hands almost evenly though it is a predominate right hand society so I mostly write with my right. Except on windows which is easier with my left. It is harder for those who don't use their left for much. Though sewing and quilting you tend to use both. I found the blades are getting cheeper especially if you buy them in multi packs. try and keep your fingers out of the way. I wouldn't want to do first aid or get blood on the quilt unless that is the look you are going for