mmmmm... mmmmmmfff...
(should have been careful for what I wished for)
By the way, I'm a ventriloquist*, so you'll just have to endure more of my soporific scientific chatter anyway.
* Not really.
Anyway, comets, contrarily to planets, have much more erratic orbits than Pluto, and, by definition, are followed by a long tail of dust. Also, they travel at much higher velocities than planets. Therefore, Pluto cannot be a comet, even though they are, like the former, mainly composed of ice.
Oh, and you alone cannot determine whether Pluto should be called an asteroid or a planet or a comet. The choice have to be agreed upon a majority of experts in the domain, and the definition attributed to the name has to correspond to the characteristics of the object, and vice versa.