Banning words from titles is not the answer. We've experimented with that already, and it's been downright infuriating if not an abject failure.
Besides, there are perfectly legitimate reasons to have "tag" words in a title. Good titles work those words into the question organically. This has been discussed before.
The only problem is when they tack them uselessly onto the beginning or the end. I can only assume that this practice comes from people emulating the system-generated page titles, to which the name of the most popular tag (well, basically) is prefixed along with a dash. Like how this question, with a good title:
Can I reliably turn a string literal into a symbol name using templates (or fancy macros)?
c++ - Can I reliably turn a string literal into a symbol name using templates (or fancy macros)?
Apparently, this is done for SEO reasons, although there is some recent debate about whether this is even helpful.
So if we're stuck with the system-generated titles, how do we fix this problem? The same way we fix all other problems with post content: edits. Trusted users can make unlimited edits to posts, and users who still have their editor training wheels on can suggest edits for community approval. These are a great way to remove those pesky tags from titles, and improve the title while you're at it. Not only are you improving the site, you even stand to gain a reputation boost if your suggestions are approved.
There are established community standards for this already that are strongly in favor of removing these title warts: