As far as I know the feature only works for things that can be entered in the filter box for tags. This means tags and genres. I only made a button to avoid entering the url every time.
If you have need for a special search, try out the third tool. It is far superior to mere tag filtering.
It has two lists and you can add items by pressing 1 or 2. And this works also if you hold the key and the item disappears and the next item takes it's place. Adds like 30 items per second. So just scroll down a few pages with auto-loading next page mode and go up again and hold the key to populate an ignore list for anything you can browse. Input methods, tags and what else. After that your normal search will have those items excluded.
Input methods are even less accurate than tags, I guess. So you might find, that simply marking games you already have checked out, to be a more convenient method.