Answer:
I can ruin your day, or darken your life. And while I'm expected, I'm never alright. I'm bad for business, and worse for your hair. Wherever I am, there's something not there.
What is full of holes but still holds water
Ripped from my mother's womb. Beaten and burned, I become a blood thirsty killer.
People are hired to get rid of me. I'm often hiding under your bed. In time I'll always return you see. Bite me and you're surely dead.
When the day after tomorrow is yesterday, today will be as far from Wednesday as today was from Wednesday when the day before yesterday was tomorrow. What is the day after this day?
People take me on walks and I run and have fun. What am I?