Disguising yourself is a great way to achieve anonymity. It is 100% allowed and encouraged, however there are a few things which apparently need to be laid out.
#1: Disguising your character's appearance is not enough. It may keep people from recognizing your face, but your size, build, and scent do not change unless emoted as such. IE *Has padding shoved in his armor to make him look bigger* *Has covered himself in deer urine to disguise her scent* etc.
#2: Voices. A character can disguise his voice. We do not require a perform or a bluff check for this. HOWEVER, there are instances where voices may not be disguised. Voices cannot be disguised when casting spells or reading from scrolls. Magic is a learned art. Even for a sorceror he must speak the verbal parts of the spell correctly in order for the spell to be activated. Basically.. if you want to be able to cast your spells while still maintaining your disguise, either cast when you are not around anyone, or take the silent spell feat and cast all your spells silently. Failure to do this may result in your character being identified by his voice if he or she is a well known character.
#3: Familiars/Companions. You may be able to disguise yourself, but you CANNOT disguise your companion or your familiar. If your companion/familiar is known and you have it out, you may be identified.
#4: Weapons and gear. You may be identified by your weapons and gear if you use a lot of unique stuff. If you walk around with a scimitar that glows with positive energy and it always looks the same, you may be identified by that scimitar. It is up to the one who is disguising him or herself to ensure their disguise is complete.. this may mean spending a lot of time and money at the tailors and armorers getting new weapons to use with your disguise, or changing the look of your weapon.
#5: Names: If you are attempting to disguise yourself, and someone in your group uses your name in an IC way. You CANNOT say "OOC: Oops! I meant to say blah!" You are caught. Now, if you are disguised and your name is metagamed by someone, then yes, you can say to that person through a tell "hey i'm disguised, you wouldn't recognize me as such" to which then they could reply "OOC: Oops, sorry, didn't notice the disguise. Disregard the use of the name"
#6: Your disguise must be believable. You cannot try to convince people that you are a giant when you are an elf. You cannot try to convince people that you are a halfling when you are a human. Well.. I guess you can try, but you CANNOT oocly expect anyone to believe you. Keep your disguises to something believable. If you are a human, choose something of human size and shape to try and convince people you are.
This ruling goes into effect immediately and IS NOT RETROACTIVE! YOU CANNOT IDENTIFY SOMEONE WHO HAS GONE AGAINST THIS RULING IN THE PAST AS IT WAS JUST NOW MADE. But as of this date and time, anyone who does not follow the ruling may be identified.
Bare in mind, it is always 110% the responsibility of the person disguising themselves to keep up the pretense.