There is a tension.
Do you keep a box of models nobody buys because you want to have a complete set, or do you let the customers, community, and publisher know that the game is not giving that box its due by dropping it? Maybe the box is not cool. Maybe the rules don't support it. Maybe it's so expensive it gets bought online at a discount. Inventory metrics lets me say, "Don't care; not my problem."
I bring this up because of a box of unloved artillery in my store and my indecision on what to do with it.
This artillery problem applies to everything in your store really, but in this case let's look at war game models. We often hit a wall where the coherency of the line brushes up against what people actually want to buy. I used to play Astra Militarum, otherwise known as men. I really liked my basilisk artillery pieces and I would regularly field three of the giant models. I mean, I wouldn't win with them, because 40K doesn't reward artillery, but they were cool.
On the other hand, I played Flames of War and used a special US commander who would drive around the battlefield in his Jeep and spot for artillery. That was his special background ability, and because Flames of War is more historically accurate, artillery was a winning strategy. I could talk about artillery until I'm blue in the face, but customers aren't going to buy it, if the rules say artillery sucks.
So do you keep the dusty box of artillery that nobody wants or do you follow your inventory reports that say get rid of it?
I'm here to say, there is no wrong answer. You may feel it is your responsibility to represent. You may also feel, after decades of dusting boxes of artillery, that this is not your fight. Someone in a board room had a discussion with the game designers and decided artillery is not what their game is about; it's about close quarters combat, and the reality of artillery would radically change the game in an undesirable way. So we have artillery in kind of a superficial way, but artillery sucks (until the optional special rulebook, when it doesn't for a little while, because we need to move those dusty boxes of artillery!).
You could argue that there is a product pyramid, product coherency. I'm sure the publisher would argue that for you. We are inundated with far too much product of all sorts, some of which, like stretch goals are really "splash" items, meant to be bought up quickly and never re-ordered again. We often miss the splash cue and find ourselves flailing in the water, rather than jumping out after the initial splash. Game store owners are sad when they're out of product, while publishers often consider it a success. We are wired to make this mistake.
There are some very brave, hard working, lovers of the community, former game store owners where this is the case. There are store owners who are passionate about games far more than about running their business. It's why game stores are such wondrous places, at least for a while. Going down with the ship is noble, but to quote Patton, "No bastard ever won a war by dying for his country. He won it by making the other poor dumb bastard die for his country." Harsh, but true.
So I guess I'm here to say you can be ruthless, perhaps you need permission from a random outside person to be ruthless. Here I am! If artillery is there to fill a hole and nobody is buying it, don't feel obligated to keep artillery on your shelf. Or dead expansions, or stretch goals, or airbrush paint when nobody uses an airbrush. Or anything that isn't performing. Let the other poor dumb bastard carry it while you achieve financial victory.
Of course, you might consider this loyalty to the box, the line, the community, a form of integrity. You have to draw the line, I suppose.