There are a few ways to make devastating dirty trick builds at that level, but what do you mean by flavorful?
A bounty hunter slayer with quick dirty trick can just wreck enemies by blinding them in the first attack and then getting free dirty tricks for every following sneak attack they get against their now blind enemy. Not sure if there's a lot of "flavor" there though.
I think Dex-based TWF-focused Brawler, Fighter, Barbarian, Ranger, Rogue, Magus, Warpriest, or Slayer make the best Dirty Tricksters. Str-based Dirty Tricksters work just fine too because Str-based is less feat-intensive, but your AC & Reflex Save suffers slightly-- so this is up to you. If you're allowed 3pp content, Psychic Warriors make amazing Dirty Tricksters. If you pick a class, and/or a "short list" of archetypes you might like to try, I'll help make some build ideas and race suggestions.
Whenever you do a Dirty Tricks build, Dirty Tricks Master is what you want to build towards. And if you don't want to build towards this feat, then you should have a good reason why not (i.e. getting far better stuff from building towards something else). Once you have the Dirty Tricks Master feat, your Dirty Tricks build is essentially complete, and everything else you pile on after that is extra icing on the cake.
Dirty Trick Master (Combat)
You are adept at stifling your enemies and can expertly make a bad situation even worse.
Prerequisite(s): Greater Dirty Trick, Improved Dirty Trick, base attack bonus +11.
Benefit(s): Whenever you successfully perform a dirty trick combat maneuver against an opponent who is still affected by a condition inflicted by a previous dirty trick (whether your own or another creature’s), you can cause the condition to worsen. In addition to increasing the duration of the condition as normal, you cause an opponent who is dazzled to become dazed, entangled to become pinned, shaken to become frightened, and sickened to become nauseated. This worsened condition replaces the previous dirty trick condition, and lasts for the duration of the dirty trick (including any rounds remaining from the previous dirty trick condition) or until the opponent uses a standard action to remove the condition (whichever comes first).
^----- The reason being that you can Sicken in round 1, and they're forced to use a Standard Action to clear the Sicken condition. If they don't, then in round 2 you worsen the Sicken to Nauseate, and now they can only take Move Actions.... and it takes a Standard Action to clear the Nauseate; so they're essentially out of the fight at this point because 2d4+2 rounds is an awful long time to be stuck Nauseated. Once a Dirty Tricks Master has Nauseated an enemy, they can choose to finish the enemy while he cannot attack back, or they have the option to attack/neutralize a different threat.
And TWF is my personal favorite way to do a Dirty Tricks build, because with Improved TWF and Haste, you can be rocking 6-7 attacks per round at level 11, and 1 of those attacks will be substituted as a Quick Dirty Trick. Once you get Greater TWF, this becomes 7 attacks, and then you get an 8th attack once you get 16 BAB. 2h Dirty Tricksters do fine too don't get me wrong, but TWF is the Cadillac of Dirty Trickster feat-chains.
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Since you're starting at level 10, I think a full BAB class would probably be best because you can get Dirty Tricks Master at level 11. Rogue, Magus, Warpriest, and Psychic Warrior get Dirty Tricks Master at level 15 because of their 3/4 BAB, so if you're willing to wait, these are good choices as well.
Questions:
1) What level you think your campaign will end (also what campaign? or is this homebrew?)
2) Anything additional you'd like to focus on? Stealth? Maybe get some SnA to capitalize on Dirty Tricks Blind?
3) Are you Multi-class-averse or is Multi-classing/dipping okay?
4) Str or Dex based?
5) 3pp content? What books are allowed/disallowed?
6) 2h or TWF?
and the big question:
7) Which class? And what archetypes of that class look interesting?
Vigilante (Avenger)
Dex-based
1 Weapon Finesse
2 Lethal Grace Talent: Combat Expertise/Dirty Fighting (B)
3 Improved Dirty Trick
4 +1 Vigilante Talent
5 TWF
6 Fist of the Avenger Talent
7 Greater Dirty Trick
8 Steel Soldier Talent
9 Quick Dirty Trick
10 Deceitful Trick Talent
Social Talents undecided
Gear:
+5 Darkleaf Cloth Hide armor (26,515)
Dueling (PSFG) Amulet of Mighty Fists (4000)
Rest in defensive stuff
***
Steel Soldier basically functions as Handwraps +5 and will stack with the AoMF for +5 Dueling (PSFG). So you'll add +15 to Dirty Trick CMB from your weapons, and the Deceitful Trick Talent in combination with Quick Dirty Trick means you can do two dirty trick maneuvers per full-attack.
This pairs very well with the Dirty Trick Master feat at lv 11 that Ryze Kuja brought up. As an Avenger you also have access to the Mad Rush talent (effectively pounce) in addition to the Animal Patron talent (+10 ft reach at lv 12) which will help you full-attack.
For a 10th level character focused on dirty trick maneuvers, a cad archetype fighter is probably one of the better choices. Dirty Maneuvers gives a scaling bonus (+3 at 10th) "on disarm, dirty trick, and steal combat maneuver checks," while Deadly Surprise allows the cad to "attempt a dirty trick combat maneuver as an immediate action" "when a cad hits an opponent that is denied its Dexterity bonus to AC" (such as after using dirty trick to impose the blinded condition).
Unfortunately, dirty trick maneuvers require at least some GM buy-in ("The GM is the arbiter of what can be accomplished with this maneuver"). If you have a GM that refuses to "allow" dirty trick maneuvers to be used frequently, then you may end up frustrated.
Grippli Vexing Mouser...
Mouser Swashbuckler 2/
Vexing Dodger UnRogue 8
The idea is to combine the Grippli's natural Climb speed with Vexing Dodger's Limb-Climber, Underfoot Trickster, and Distracting Climber abilities... Mouser's Underfoot Assault sets everthing up very nicely. If you continue past level 10, take 5 more levels of Mouser to get the Hamstring Deed. You will probably want the Agile Maneuvers feat, and take Climb for your UnRogue Skill Unlock. The Grippli alternative racial features Glider and Jumper allow you to Climb all over the largest [even flying] enemies, stabbing all their vital organs in alphabetical order, then do backflips off of them, sticking the picture-perfect superhero landing every time.
Or... Kobold Vexing Swarm Fighter...
Vexing Dodger UnRogue 5/
Swarm Fighter Fighter 5
The idea is to combine Vexing Dodger's Limb-Climber and Underfoot Trickster abilities with Swarm Fighter's Athletic Prowess, Share Space, and Strike the Underbelly abilities. If you continue past level 10, finish strong in Swarm Fighter Fighter. I like working towards Coordinated Charge for the Teamwork feats... a bunch of Kobolds climbing all over an enemy like Compies from Jurassic Park... it's absolutely fabulous, but requires a bunch of Kobolds [which may, but probably does not, fit your party].