Comment 5 for bug 874409

Changing the meaning of -qq might have worked thirteen or maybe even teen years ago, now everything (and your dog) depends on that behavior, so you will make a lot of people and scripts very angry for literally no reason. As i already said, the complete description of -q is "produces output suitable for logging, omitting progress indicators." It doesn't say no progress is visible, it just says that it is possible to log this output and that "indicators" are omitted. It can't get much clearer than that. At least i don't see how, do you have a recommendation for a better wording?

And -qq actually answers your question:
apt-get whatever -qq
will tell you if the request was successful or not and if not it will tell you also why -- no output is a good thing for commandline applications. If you want output add something like
 && echo "successful" || echo "failed"
to your request. That's also why i said that "already installed" is not an error, as if it would be an error you would get a "failed" here even through the request is satisfied and therefore successful.