Since I made a comment about server hits let me stand by my claim that not searching for something mafia believes is not there saves hits compared to searching for something mafia believes is not there.
Why is it of benefit to a user who is not engaged in spading or discovery to search for mallable items that are otherwise unknown to mafia? The only reason that I can see is because the user knows about the item from some non-mafia source and wants to purchase it. That functionality currently exists so long as the user uses the relay browser and not mafia's purchase tab. If the user does that then the item will be in inventory but it will still take some action (such as refreshing the inventory) before mafia knows about the item and even then, if the item is consumed or otherwise disposed of, mafia will have to relearn of its existence.
So the (only) "normal" user who benefits is someone who sticks to point releases, knows about a new item and the item is consumed or otherwise used on a daily basis so that it is constantly being forgotten and relearned. If this is not changed then the user either has to use the relay browser or has to learn a sub-string that the new item has in common with existing items so that a search from Purchases will discover it.
A previous solution, data override files, seems to have caused problems that were worse than the ones the overrides solved.
The problem only exists from the time KoL releases a new item until the time that the user adopts a point release that knows about the item.
I guess the bottom line for me is that I don't think this is a particularly huge issue that has to be solved in code. We know when it might occur, we have work-arounds we can tell people to use when it happens and we can make the problem go away as soon as people adopt a more recent daily build.
I do believe the feature is beneficial to spades and the kind of people who are going to going to do vowel searches anyway, so what underlies my opinion is the question of which particular subset of the user community should be catered to?