Often games require the use of stairs or ladders to progress or explore levels. Yet the ladders seems to be an after thought for the game developers. The interactions with the ladder are unclear and require the player to unnaturally align with it hoping a menu pops up. In some games the ladder or stairs will be a source of fear for the player. Either the player is unable to grab hold of the ladder or when they do, they aren't able to get off safely. The same can happen with stairs where small glitches will cause you to die. When simple game mechanics like this break the entire play experience can be ruined.
Arma 3 Edit
In Arma 3 interacting with stairs and ladders can be the players undoing. In multiplayer situations where your gear has to be earned dying can set you back hours. When trying to dismount ladders the player often will glitch off the building and fall to their death. Arma 3 Ladder Interaction It is often impossible to find the indicator to select the ladder as well. People often get stuck on top of buildings unable to access the ladder.
Day of Defeat: Source Edit
In Day of Defeat: Source, there are many custom maps that are created by members of the community and many of these maps have terrible climbing mechanics. When climbing out of water for example, sometimes the player is not able to get over ledges and instead ends up falling back in the water. What makes this worse is that the mechanic shoots the player above the ledge when attempting to climb out, making the player very vulnerable to being killed while they're stuck climbing. So not only does the player have trouble climbing to flat surfaces, but there is also a high chance that they will be killed if the climbing mechanic isn't smooth. This can be cause frustration for the player, especially since it is not the player's fault.