I hate the 270 - It's marginally smaller than a 7mm, being .277 vs .284, yet it tops out at a 150gr bullet whereas the fractionally larger 7mm can handle 175gr. I just think there are better calibers adjacent to it.
The Creedmore, the PRC, the 6.5x284, and all the rest. There was and is nothing wrong with the 6.5x54MS and the 6.5x55. Everything since is a retread. Stick with the original champ and don't act you invented the wheel Mr. Creedmore, you stand on the shoulders of giants.
The 280AI, 7mm Rem, 28 nosler, 7x61, 7STW, and all the others. Marginal improvements on the 7x57 and 7x64 that were already around.
The 338. Its not a 300 win mag nor is it a 30-06, nor is it anywhere near as good as a 375HH. It just feels like it is a lid for a pot that doesn't exist.
Anything that copies the ballistics of an original safari load. 375 Ruger, 416 Ruger, 416 Remington, can't we just stick with what worked for a hundred years and does the same exact thing?
Weatherbys. If you need a Weatherby because the equivalent caliber non-weatherby isn't enough, can't you just step up a caliber and call it a day? It seems like a lot of pain and effort to make a small hole when I could make a much larger hole with the same recoil going to the next proven cartridge.
And anything made in the last 30 years. They almost all end up being fads that burn out and fade away. Things ending in WSSSM, RSAUM, WSM, that stuff.