Seconding that. A passport agent will accept whatever picure you give them however DOS (state) is the final say on whether you get your passport or not. Generally I'll advise a applicant the same thing if I see a tank top or low cut shirt. We won't however get into an argument over it and will send it in knowing darn well it won't be processed. Please use commone sense and listen to what the acceptance agent tells you. They are there to help get you your passport, not make life difficult. It can take weeks for even a rejection to come back. Delay delay delay.
There are all sorts of other complications that can come up during the application process that everyone needs to be aware of. These issues may pertain to some of the parents on these boards.
If you're a single parent please be aware that you will need the consent in writing of the former spouse to obtain a passport to take a child out of country. Obtain a form from your local acceptance agency. This law prevents a parent from skipping country with a child and child abduction cases. It also can be a pain in the rear end for a lot of folks. Talk to your local agent if your case involves not having a clue where that spouse is these days. I deal with military spouses all the time that have husbands deployed and they're trying to get overseas to see them while they're on R&R in a different country. General power of attorneys that give them all legal rights don't even work unless there is a specific line stating he/she gives there spouse legal authority to obtain a passport. Believe it or we do get ahold of the spouse through there command. If you're military you might keep in mind adding this if you end up deploying. Saves a lot tears for your spouse.
Also if you owe back child support and are applying for a passport be aware you will not be issued a passport. All applications are run through state checks. Until that child support is payed and the system updates(which can take awhile also) they cannot issue.
Last major issue off hand I can think of right now. If you have had a passport and have misplaced lost it (and it would still be current) be aware you are going to have to fill out a form giving a detailed summary of what you believed happened to it. Not just "I lost it". They'll want to know as many details as to where it might have been lost, the circumstance around it, so on and so forth. Detailed records of every passport issued are kept on file. The main concern here is a valid passport falling into the hands of someone who would like to do people in this country harm.
Hope this helps or heads off potential headaches.