"Reports" always seem to emphasize that the object's observed movements wouldn't be possible for a plane, helicopter, or balloon. A kite never seems to even be considered, which makes it perfect for a hoax.
Free-floating objects are routinely reported as UFOs. We had a spectacular one a few years ago in my city. It was a silver hobby dirigible approximately 30 m long that had escaped its owner's control.
A number of premises underlie most UFO reports. A number of them simply don't hold when scrutinized.
Foremost among them is that ordinary objects will always (or almost always) be recognized as such, especially by experienced observers. The corollary to this is the notion that ordinary objects will always manifest in their canonical appearance. The mantra goes, "I've seen many examples of X before, and that was no X." The expectation is that X will appear and behave in a sort of canonical form: helicopters will
always make loud chop-chop noises, etc. I've been around airliners my whole life, with considerable hands-on experience. When you see an airliner emerge silently from a fog bank with only its landing lights visible, your whole notion of "I know what X looks and sounds like" goes out the window.
Around my home, the most common source of UFO reports is seagulls. Our state bird is the California seagull. There are lots of them, especially around the lake. As you may be aware, flocks of birds tend to wheel more or less in unison when they turn. The Califonia seagull has a dark back and a white underbelly. This means that when seen from a distance, a flock of seagulls will tend to appear and disappear against a mountainside backdrop.
The next common misunderstanding is that size, distance, and velocity can be reliably determined. This is especially acute for unidentified objects. Beyond about 100 meters, estimates of distance become highly inaccurate. The customary binocular vision cues are not useful beyond that range. Neuroscience shows us that estimates of distance beyond 100 meters is based almost entirely on estimates of object size. More particularly, you have to know what the object is so that you can reckon its apparent size against expected size. Experimenters have routinely spoofed subjects' estimates of distance by showing them objects of familiar shape but nonstandard size.A big part of this cueing mechanism is fitting the object within expected surroundings. When you present objects outside their familiar background or context, estimates of size go out the window as well as ordinary object identification. Estimates of velocity depend on accurate estimates of distance and a relative lack of motion in the observers. Moving observers (e.g., objects seen from a car or an airplane cockpit) routinely appear to exhibit motion that is inconsistent with naive estimates.
Finally we have the myth of the "trained observer." While certain kinds of observation can be trained, there simply is no such thing as a generally better observer. This includes pilots, military officers, government officials, police officers, and others common proffered as people whose inability to identify something should be considered evidence of some unknown of fantastical origin. The kind of observation that can be trained is situational and phenomenological, not general. For example, police officers can be trained to recognize signs of drunkenness, and this can be tested and established to a higher degree of accuracy than lay observation.