I've already tried putting terms within quotes but it usually makes no difference.
Putting one of your search terms in quotes should prevent category changes -- and has done so in the past -- but it appears that eBay has recently changed something so that does not always work anymore.
I've oftentimes wondered if it was possible to add exclusions as you've mentioned, as I don't know how to do this, at least not on this site.
You can exclude items from your search results that contain a keyword by putting a minus sign in front of that keyword, like this:
bookcase -octopus
That will find items containing bookcase in the title or item-specifics as long as those listings do not include the keyword octopus. Using an exclusion does prevent automatic category changes and keyword substitution, and such a search should wind up in "All categories" even if a search for bookcase alone winds up in a specific category.
https://www.ebay.com/sch/i.html?_from=R40&_nkw=bookcase+-octopus&_sacat=0&LH_TitleDesc=0&_odkw=bookc...
Your advice is good, but I never had to try any of this when searching prior to maybe a few weeks ago, or so. Whatever changes the coder or webmaster has made to eBay's search function have not been beneficial. Whether they're technical glitches or deliberate changes, I would like to see eBay roll them back so that the search function works as well and easily as it used to.
It appears that eBay has made some changes regarding how searches work recently. Whether those changes are intentional or the unintended side effect of some other update remains to be seen. If they are the result of an error, eBay may fix the error at some point, if enough users notice and complain to eBay. Such corrections, if they happen at all, may not happen as quickly as many users would like, though.
In the mean time, while you are waiting for eBay to fix things, there are search techniques you can employ right now to still get the most out of your searches, regardless of what eBay does.
