When placing a comparator adjacent to a Command Block, if the Command Block successfully executes its command, it is supposed to emit a 'Success Count' signal with a strength equal to the number of successes in that particular operation, in accordance with each command's success criteria.

Under Commands ( http://www.minecraftwiki.net/wiki/Command ), the criteria for a successful '/clear' command is as follows:

'At least one item must be removed, and playername must be online.'

While using the Command Block with instructions '/clear @p[r=5]' it would consistently output a Comparator signal even if the inventory of the player inside its radius were already empty. Further, given specific ItemIDs to clear '/clear @p[r=5] itemID' the item will be cleared the first time the command block receives a redstone signal, but with the second pulse of the signal, even though the item is removed completely, it still emits a 'Success Count' through the comparator.

I cannot imagine this is designed behavior, as it is in direct violation with the success criteria for a /clear command. Just want to make sure this isn't a bug, maybe I'm misreading something or doing it wrong.