Parting Thoughts counts every kind of counter on that creature. Effects such as that of Giant Growth, Auras, and Equipment arenâ€™t counters.
Parting Thoughts can target a creature without any counters on it. Youâ€™ll lose no life and draw no cards.
If a creature has +1/+1 counters and -1/-1 counters on it, state-based actions remove the same number of each so that it has only one of those kinds of counters on it. There wonâ€™t be any counters of the other kind for Parting Thoughts to count.