Toothpaste stains can be a total pain, in fact, any stain can be really annoying but toothpaste probably takes the win. That is because some kinds of toothpaste contain titanium dioxide powder which leaves really hard-to-remove spots.
In order to remove them easily, simply mix a bit of stain remover or some detergent with water. Afterwards use a clean cloth to put the mixture on the stain.