I was a door-man in the 00's and still run door occasionally for a friend's bar on big weekends.  In PA, most of the things in this thread should pass.  There are only 4 acceptable forms of ID as decreed by the Pennsylvania Liquor Control Board (PLCB):
1. A state-issued Driver's License
2. A state-issued ID Card (i.e.: a non-Driver's License)
3. A passport with stamped VISA (even if it is a US passport)
4. An active duty (green) Military ID

For all of these, the have to be non-expired.  They have to be non-duplicate.  For the military IDs, they have to be the Active Duty IDs (not the family (Brown) or retiree (Red/Blue)).  The passport MUST be non-expired and be stamped with a VISA (this one always bothered me for the US passports, but I don't make the rules).

As far as detecting fakes, the most common fakes just have the wrong backs or the wrong holograms/blacklight markings.  But fakes are rarely used.  The most common way is to get the ID of an older sibling or a friend that looks similar to you.  That's why duplicates are not allowed.  If you have a duplicate, the bar may ask for more types of IDs to verify who you are.  Another form of photo ID, multiple credit/debit cards, signature match.  One of the big things is asking the information on the ID, but out of order and watching them to see if they have to rattle through the whole thing in their head to get to the right answer.  Ask things like "What is your birth year?" followed by "What is your house/apt number?" then "What is you height?"  Comparing eye color and height is usually a give away as well.  But, beyond that, they can just say "no. We don't have to accept duplicates.  We have enough customers in here tonight.  Come back when you have a valid form of ID."

On rare occasions, we'll call the cops (or the PA Liquor Control enforcement: PLCE) and have them come verify the identity.  I've done this roughly 40 times in my life and only been wrong once.  I always tell them at that point, "You're welcome to stay here.  If I'm wrong, your first drink is on me, but if I'm right, you're going to end up arrested.  I'd recommend you not being here when the cop arrives if this isn't you; they won't be able to track you down and arrest you..."  Surprisingly, about half stayed, thinking they would bluff it out.

Also, bars (in PA) are allowed to confiscate your IDs if they think they are fake.  We get that argument a lot of "I paid for that!  You're stealing!" or "That's my ID.  I can't drive without it" or even "Ok, you got me, that's my brother's.  He'll kill me if I don't bring it back!".  Unfortunately for them, bouncers are paid bounties for fake IDs (usually $25-$50 per ID) for eliminating potential risk in the bar.  Fines can be up to $1000/drink served to an underage patron for everyone in the liability chain (bouncer, bartender, waitress, manager, and even the owner).  We are supposed to turn them into the PLCE or local police "in a timely fashion" (usually at the start of each week) and they are responsible for returning the real ones (if they think it was in error instead of someone else using it).  Most of the time, they let the bar keep a bunch of the fakes to use for training new bouncers.