Development Hell: The blinkumentary. Documenting the band's return and the production of Neighborhoods, development had went on for a few years. The last anyone has heard of it from the band itself was them getting to watch a near final cut of the film...then nothing. Perhaps it's now on the The Shelf of Movie Languishment, perhaps their former label didn't approve, maybe the band themselves just thought it really sucked.
Old Shame: Averted with Travis Barker's previous stint with The Aquabats!; while there was previous beef due to the circumstances of Travis leaving the Aquabats, both bands are back on amicable terms to the point where the Bats opened for the last two shows on blink's reunion tour.
Whilst there's no indication any members of the band feel this way, Tom joked on the Enema of the State II DVD, that he can never do anything like run for political office, because the stuff he's gotten up to as a member of Blink 182 would provide easy ammo to destroy his campaigns.
Some of their reactions to their older material can be seen as a mild version of this. Being pigeonholed as a joke band/simply a pop-punk band made it considerably more difficult to be taken seriously by a lot of their fans and the media when they tried branching out on later albums and their side projects. When it comes to live shows, Tom would prefer that the setlists were comprised mostly of songs from the Untitled album onward, while Mark knows riots are likely to ensue if they didn't play the more popular older songs. It's a strange balance they have to keep.
When it comes to aliens, cryptids, conspiracy theories and stuff of that nature, Tom genuinely knows his shit to the point of being a featured guest on Coast to Coast AM and other shows focusing on those topics. After meeting with Dr. Stephen Greer (of The Disclosure Project) and receiving UFO documentation from him in the late 90s, Tom attempted to get a show pitched about Greer's findings to MTV and his receiving the information may have led to his landline being tapped for a few years. His usual justification for the existence of alien life is actually a highly simplified version of the Drake Equation. His interests are fairly understated with blink (beyond the song "Aliens Exist" and his interviews in Riding In Vans With Boys), but that's because he has a whole 'nother band to openly mess around with that sort of thing.
The entire band played BlizzCon in 2013. Not to mention that even though Travis Barker is near unanimously agreed upon to be a total badass, his being the Baron von Tito doesn't make that any LESS so.