Polymorph as a Spell-Like Ability

[Edweirdo]

If a creature has the ability to use Polymorph at will as a Spell-like ability and he intends to use it to blend in among other species or cultures, i.e. an Outsider who lives among the humans of Golarion as one of them, how difficult would you make it for him to maintain it?

Does he has to take a six second pause every time he renews the polymorph as it runs through it's duration as the day progresses? Would this be noticeable to those interacting with him?

As he renews it are there subtle shifts in the new version of the spell from the previous version that astute observers would notice?

How difficult do you forsee this being for the creature in question to pull this off for extended periods of time?

[Speaker for the Dead]

I guess there's no reason that he/she/it couldn't re-cast the spell before it's duration expires. How many times a day can your creature use the spell like ability?

I'd have them make a disguise check (with the +10) to maintain a consistent appearance and to match mannerisms etc.