While I of course do not purport to know more than anyone else about UFOs,
there are certain logic elements that anyone can pick out. Here is a top ten list.
1. If UFOs travel from distant planets outside our solar system, they most assuredly have technology FAR in advance of our best technology. That would include stealth. So it is implausible that we could ever see the aliens at all. Or, if we could see them, then we should be seeing them under conditions that no one would deny happened. The idea that "We will let you see us, but we'll make it look like we are hiding," is the least plausible of all possibilities.
2. Their (the exo-civilizations') technology is most assuredly superior to ours not only in stealth, but also, in every endeavor we make.
3. In all likelihood, exo-technological exo-civilizations are capable of synthesizing from mere hydrogen any element, any compound, indeed any substance which they wish to create. They likely have also mastered things like dark matter, or other fundamentals of physics about which we have no clue.
4. Therefore, they do not need anything from us. Not water, not food, not even our planet, since they could probably tailor-make a planet to suit their needs.
5. The only imaginable motives they could have for coming here would be to gather esoteric knowledge, pure science, or curiosity. Perhaps they have motives we cannot imagine.
6. Futurists now point to a probably inevitable event in any technology--- an event called the technological singularity. Briefly stated, when we become utterly dependent on artificially intelligent computers to sustain us (as we already are for many aspects of our infrastructure), then ANY human (or biological) society must become suddenly and without warning overwhelmed. The result is inherently unpredictable. This will be especially true when quantum computing makes a breakthrough.
7. The tech singularity might come about gradually if humans (or exo-creatures) incrementally combine with their technology--- for example, implanting computer chips to enhance their brains. Even then, the results are inherently unpredictable to the present state of the human mind.
8. We must conclude then that the UFOs are not avoiding us, and also, that they are neither ignoring our ability to see them, nor wishing to be seen. We should see them either frequently and under provable conditions, or never.
9. Since the record of credible sightings does not fit any of those conditions, we must consider the possibility of the UFOs not being under intelligent control, but rather, being some kind of high technology "junk." By that is meant, some kind of technological implement or experiment that was discarded and was never expected to become autonomous. An exo-civilization experiencing catastrophe might be the source of such "space junk."
10. While this explanation of UFOs is not completely satisfactory, it is better than the present idea, that high technology capable of interstellar travel could not master so simple a technique as avoiding detection.