WHETHER it’s the Dyson or Revlon’s 2-in-1 dupe, the internet is crazy for hair-drying brushes. Giving you the ultimate blow-dry effect from home, they’re the tool that combines the hairdryer and the round brush into one – hot air comes out of holes between the bristles to dry and smooth your hair in a single step. Some brushes even rotate to make the process easier. It’s an idea...