The Combat Feat "Dirty Fighting" (https://www.d20pfsrd.com/feats/combat-feats/dirty-fighting-combat/)
Source: Paizo Inc. - Pathfinder Player Companion: Dirty Tactics Toolbox, p.14
In the "Special" Description states:
"Special: This feat counts as having Dex 13, Int 13, Combat Expertise, and Improved Unarmed Strike for the purposes of meeting the prerequisites of the various improved combat maneuver feats,* as well as feats that require those improved combat maneuver feats as prerequisites.*"
So it should help meet the prerequisites for example: "Improved Trip" and "Greater Trip".
ie Prerequisites for "Greater Trip" should be: Dirty Fighting (Combat Expertise, Int 13) + Base Attack Bonus 6 + Improved Trip
I know that's not how it should code (i'm not a programmer) just my thought process. The bolded text is also missing from the feats description in PCGen.