As I mentioned in another post even if this is interesting I feel that it might end failing due to feats being valuable depending on the rest of the character options and there being to many feats to really consider all the interactions.
For example a 1st level half elf (because they are so OP) warlock can get a really good use of skill focus [bluff] and deceitful
Could have a charisma of 18 (not even going for aging) mod =+4
Bluff ranks +4
Skill focus (bluff) +3
Beguiling influence +6
Master work tools +2
That's a 23 mod and supposing that you roll a 1 on the check it goes up to a bluff check of 24. The bluff penalty to "almost too incredible to consider." is -20 (drops the check to 4) so unless the opposition has ranks in sense motive and a decent wisdom its going to outright believe your bluff in a roll of 1.
If flaws and traits are on (or just be human) you can raise the bluff check higher be it via silvertongue mask (shape soulmeld) or nymph kiss or even using traits to increase it.
If you don't consider age penalties cheesy well that adds some more too.
Does that make skill focus a strong feat? For that level 1 example, sure, it is, for anyone else? No.
Edit: Actually checking my numbers the half elf still has 1 feat point left so he can grab any feat that he wants (he will contract a debt, but who cares) let's say nymph kiss for another +2. Now he has a bluff check of 26 (rolling a 1) and the opposition has to have 4 skill ranks in sense motive and 14 wisdom to be able to not believe the most outrageous lie.