The word comes from the Greek. It means "messenger" or "sending" and implies not only the bearer of the message from the source, but also in a way the message itself. All well and good when the message is good news. Gabriel goes to Elizabeth, and then to Mary in order to announce that God will cause them to conceive and bear sons whose heritage will not only change the world, but save it. An angel comes to Peter when he is in prison facing a condemnation from Herod much like that his friend James experienced, and he is delivered from that fate, being brought out from sleeping-chained between two guards-without a single alarm being sounded.
These are angels we wouldn't mind seeing. In my mind's eye, they are reassuring in aspect and calming in appearance. They probably look as we would want an angel to look: beautiful, serene, presenting a pleasing, attractive, human-esque aspect. You know, like those baroque angels that sit on top of Christmas trees. We like those angels, would welcome them into our lives.
If we accept the existence of angels, and if we believe in God and embrace the Bible then we must acknowledge that God's messengers do move in our midst. There are some angels that I do not want to meet. There is the "destroyer" of the night of Passover. There is the one who wrestles with Jacob and with a touch puts his hip out of joint and gives him a limp for the rest of his life. Any one of a host of angels whose task it is to impose God's will, when the will's intent is not rainbows and unicorns for humanity, is not an angel I desire to meet.
I don't want to meet the messenger God sends to impose punishment on Israel after David chooses to sin and conduct a census of all Israel. David is given a choice by God, via the prophet Gad, that punishment will be either three years of famine, three months of David's household running from his enemies or three day of plague for the nation.
Which would you choose?
Yes, there are some angels I think I would prefer not to meet.