Is a cheater ML the worst of all?

After reading many manhwas, I just had this thought. For me, cheating is the last straw. Like how I can digest a ml being a murderer but not a cheater (only in manhwa)
So what is the bottom line for you guys? Is it the same? Or are you ok with a cheater ml as long as he gets redemption? Is it something else you draw the line at?

P.S.: this is only pertaining to manhwas and fiction. Not real life.