I have heard another person with this opinion. To settle the question, though, just do a word search on a Bible site, and look at all the passages that deal with angels, ie: Sodom and Gomorrah, the Passover, Isaiah 37, birth of Christ, etc. Holy angels (God's) are clearly either seen or unseen. Angels are messengers concerning God's people. Arch angels seem to work more directly with God (Michael, etc).
There are other angels mentioned in Scripture that aren't holy angels. It is important to understand this, that there are holy angels, and unholy angels. One serves the Lord, the other serves Satan. Therefore, technically, your statement could be correct, as the fallen angels (Gen 6, II Peter, etc) could be using the disguise of "UFO's." See the work of holy angels, and how they appear as men, while the unholy type seek to spread "deception."
"Take heed that ye be not deceived"