It is going to take a lot of kills before you see your faction move to "glowers dubiously". Save those scalps (both gnoll and orc). Once you are in the dubious range, your factions move much faster and you will find you are amiable in no time. Like Val said, once you are dubious or better hand in the scalps for additional factions. Scalp turn-ins result in only positive faction adjustments, adding to highpass faction as well as qeynos guards (corrupt) and freeport militia.
One other thing: there is a small cave just before the Highkeep Gates (orc side) with 4 bandits in it. You can kill them also for positive faction hits to highpass and others. Be aware, if you pull one, you get all 4 generally.
Getting non-kos highpass faction was a significant event in the old days when we needed to travel through there to cross Antonica. I remember it fondly :)
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