I've refused to raise somebody but only when they are either dying constantly and wasting my mana from raises or because they are one of those DPS who die constantly and don't shut up when they do with "Raise....Raise me....Omg bro raise wtf!" some people have no patience or they are selfish and don't understand the Healer has an obligation to the rest of the group to not let them die before picking somebody else up XD.