Well I use different kobolds for each type. I have enough.
I also don't like the fact that a fighter can say "I swing at the skirmisher and cleave into the minion." I don't mind if he figured out which is the minion, but if the Player can determine the differerence just from meta game knowledge and (knowing that they only have 1 hp) so cleave will kill it is a bit unfriendly to the minions.
The minions are a road block at best and usually are only meant to grant some sort of bonus for the real threats... combat advantage... mob bonus to speak of.
My minions fortunately were blessed by the wyrmpriest and most had 5 temporary hitpoints. This actually caused a minion on more than one occasion to survive a hit.
I describe the figures when I place them on the battlemat, I tell players the armor, weapons, colorations, etc... I don't tell them if they are a minion. I usually describe the elite or special enemies... 2 swords, pike, hurlers, slingers, wyrmling etc.. more specifically and usually use an obvious figure. I would try not use the same figure as a minion. I however do use multiple different figures for my kobold minions... the skirmisher, the soldier, the miner, and the trapmaker. This ads some varierty and confusion for players but it also prevents me from having 10 kobold soldiers on the board easily identifiable as minions.