I wouldn't scoff at an invisibility spell. Of course I'm aware that it cannot make you physically invisible, so you can sneak into the safe deposit vault of the Swiss bank or play peek-a-boo in the ladies room.
But it makes me a bit uncomfortable because I get a terrible feeling that it may turn you into a nobody. People will hear you but will not listen, people will see you but wont notice you (unless you choose to do something drastic, like step out in the nude or be where you shouldn't be). Basically people won't care about your whether you exist. However, you can't get away by not doing what you should or doing what you shouldn't. With an invisibilty spell casted on yourself you will not get the recognition you deserve.
In my opinion an invisibility spell is more of a hex
Please don't try these stunts on yourself and specially not on others. Because if you can do this to someone, someone can do this to you as well.
Magic, if you're not careful, can backfire and backfire badly.
This is just a different point of view.