The narrow anthropocentric view of classical Ufology had created an army of UFO/ET believers with a very strong “nuts and bolts” expectation, this expectation had drive them to give wrong and narrow interpretations to the things that they had witnessed. These are examples of that expectation at play.
1- The classical glowing dot at night, without any structure details is called a “craft” many times.
2- An object in daylight not visible to naked eye but visible in infrared will be “cloaked”. But that is wrong because many mundane objects in daylight will be visible in infrared but not to naked eye as some stars and planets.
3- When an anomaly is seen flaring from afar some people will say that this object fired its “thrusters”.
4- When an anomaly is seen releasing secundary objects then it will be a “mothership”.
5- When a highly reflective object is seen then the object is “metallic”.
6- When a group of objects is seen it will be a “fleet” or a “formation”, the possibility of a flock is never considered.
7- When rapid flying maneuvering are seen in an object then: the object is “intelligently controlled”, the idea of birds with autonomous flying is also never considered.
8- When seeing a glowing dot moving at night then, without really knowing the distance to the object, the object is assumed to be in space and since it looks big in the very poor optical magnification equipment used it should really be huge, a “huge spaceship”.
I am sure that you can add more examples of this list of very narrow preconceptions/expectations at play.