Wasted Votes are any votes in an election that are for a candidate that loses or any surplus votes in an election for a candidate that wins. While not necessarily a bad metric when that shows an electoral system is bad when a single winner election is necessarily ie the in an election for the leader of a country a very high proportion of wasted votes could mean there is very high support for one particular candidate, in such an election it's impossible for the proportion of wasted votes to drop below 50%.