I've never seen a boletus which stained red, but according to several of my books there are two important characteristics to look for in determining the edibility of unknown boletus species. You should avoid any which have red pore mouths, and any which very rapidly stain blue. Many boletus with flesh which slowly stains blue or lilac after bruising or exposure to air are good to eat.
As with any mushroom it is safer to know exactly what species your mushroom is but sometimes the Slippery Jack group are quite confusing. By avoiding the above characteristics (which work for Boletus only, not gilled mushrooms!!) you can safely try a new Boletus to see if you find it good to eat. Edible does not necessarily mean tasty and not everyone agrees on which mushrooms are worth eating.