I wish I could remember the name of the show but I believe it's on either Nat Geo or the Science Channel. . . a team of guys that interview and research sightings all over North America (mainly). Their research has revealed that less than 3% of the reported sightings they encounter are anywhere close to "possibly genuine" and that percentage drops drastically when you get into Mexico and much of the Central/South American territories. . . in one case they proved that a guy in Mexico City was naming everything in the air a UFO. . . even an obvious cluster of balloons.
Situations like the big V shaped object in Arizona, New Mexico and Florida have strong plausibility and loads of questions in that they are so unique and really don't fit any KNOWN aircraft and that's the key here -- KNOWN Aircraft.
When I was in the Navy and on watch one night in Fallen, NV. I was told that at a particular time I would see a UFO at a specific spot over the base and I was to not report it in my log, they even told me what this thing would look like. . . that was before the SR-71 was declassified however
Then again, a few friends of mine that work with NASA & JPL have had me participate in a few "experiments" given where I lived in the desert outside Las Vegas and the fact that I had relatively decent clearance. . . I can't say a heck of a lot but I know what bin Laden's crew didn't see us coming
Really... Bill had me step outside my trailer one night and see if I could hear or sense anything unusual in the area. . . I was on the phone with him the entire time and after about 5 minutes he starts laughing like a mad-man and tells me to look straight up. . . there was a helicopter... completely silent, virtually unnoticeable at a passing glance and best of all, you couldn't feel a down draft with the thing roughly 20-30 feet over head. My point being that WE have some very amazing things out there and there is more on the horizon that's simple unbelievable. . . including a new type of "dirigible" that's simply massive.
While I doubt the Seals visiting Osama used the "stealth" system this particular helicopter encounter had to offer, it's interesting to know that such abilities are in the works (and what I'm talking about happened closed to 15 years ago) and what I was allowed to see ain't not'n when it comes to the really spooky stuff @ Skunk Works