Limits of the bluff skill

[The Human Diversion]

A little background:

I have a cleric of Calistria in PFS. He's modeled after Gaius Baltar from BSG (specifically season 1 Gaius). He's a womanizing, conniving, lying, cowardly jerk. I've maxed his bluff skill out as it seems to fit his personality (max ranks, appropriate feats and traits). In any given social interaction it's his go-to skill.

Here comes the problem - I've had GMs tell me that I can't use bluff in certain situations because I'm actually attempting to improve someone's attitude toward me, so I have to use diplomacy instead.

I guess basically what I'm asking, is, can bluff ever substitute for diplomacy, or do you ALWAYS have to use diplomacy when trying to improve the attitude of a creature toward you?

[Lab_Rat]

You need to use diplomacy.

However, you could use your bluff skill to make the NPC believe you are someone special/grand/important and get a bonus to your diplomacy check.

[Adam Ormond]

Bluff is for telling believable lies. Gaius would have high Diplomacy and Bluff.

[VRMH]

The Human Diversion wrote:

do you ALWAYS have to use diplomacy when trying to improve the attitude of a creature toward you?

Or Intimidation.