FYI: This type of bad tag is called an intrinsic tag and there is a feature specifically to blacklist that kind of tag. It can be found in the moderator links as [“Blacklisted User Input”](https://dsp.stackexchange.com/admin/blacklist). (I can't actually view that link, not myself being a moderator here, but I guess it will turn out to contain “dsp” but not “signal”.)

Moderators may [ask for tags to be added to this blacklist](https://meta.stackexchange.com/a/218532/159388) but cannot do it themselves.