I recall a recent discussion about this issue in this forum, but for whatever reason I can't seem to find it.
Anyway, if my recall is correct, precanceled stamps (even with original gum) are considered USED because the precancel overprint invalidates them for postal use by the general public. Of course, one could argue the other side of the coin (er, stamp) as well, but precancels are generally considered to be of lower value than a used stamp of the same series that is not precanceled.
On the other hand, a precancel collector may attach a different value to the stamp depending on the desirability of the precancel type and/or city/state location. However, most precancels were issued in such quantities that values for most examples are relatively low, and the few that do command significant premiums are relatively scarce items.
Edit: Just found the previous thread on this discussion ... there are as many opinions on it as there are collectors:
https://goscf.com/t/13536