"This is badly designed because...
...there's too much luck involved!"
...it's not balanced!" (Wait for it... there's an explanation in the text below)
...it should be longer/shorter!"
...it should be like this other game I like!"
Usually people are commenting on their own taste in game play, not on what is a quality design. And while there are some things that you can talk about objectively, the trick is to know when you are doing that, and when you are talking about your preferences.
Something you could try is adding, "for my tastes" to the end of every analysis you do of a game, to get used to the idea that that might be what you are talking about.
Other things you could add are qualifiers about specific things, like, "this game is too long for people who like games but only have a little time per week to play," or, "the reading level in this game makes it too hard for children younger than 10, or people whose language is different from the language the game is printed in." (Which has happened at parties I've been at: non-native speakers will skip certain games because they can't understand what is going on) or "this game has dice in it, which helps some players relax, because they don't feel the pressure that it is all up to them, but also frustrates other players because they like everything to be about their own decisions."
To think that there is an exact amount of luck in a game that makes it perfect is to overlook a couple of things. 1) that the amount of luck desired varies player to player because they play for different reasons, at different times, have different personalities, and so forth, and 2) the amount of luck chosen by the creator of a game is not simply because it fit precisely with dry mechanics, but also because of the feel that designer wanted to give the game. Other designers might choose to give it a different feel because that is how they want it made, according to their sensibilities as a creator, what their goals are, what their employers are asking for, and so forth.
Sometimes, when a player says a game is not balanced, or is "broken", it is code for "I didn't figure out the most effective strategy and I feel frustrated", which is referencing a preference or tolerance about game play. Some people don't mind not figuring out a good strategy on the first play, some do. The difference between a player who says that after a session of a game and a good designer is that the designer hopefully considered the balance of strategies and powers, and played the game a lot to see if anything was out of whack, degenerate, and so forth. If after a bunch of plays, you notice that there is only one strategy that wins the most effectively, you do probably want to change that, so that there is more play to the game.
Some people like a game when they don't know what the best strategy is yet, and some people like to know ahead of time, or at least feel like any strategy they pick on a first play will be viable. Some players like to play new games all the time to try and learn new strategies, and some people like to play a game they know over and over and learn more about it. And of course these things describe a large continuum, not just paired opposites.
Some people like a game when they don't know what the best strategy is yet, and some people like to know ahead of time, or at least feel like any strategy they pick on a first play will be viable. Some players like to play new games all the time to try and learn new strategies, and some people like to play a game they know over and over and learn more about it. And of course these things describe a large continuum, not just paired opposites.
Once you separate design choices from personal preferences about game play, it increases your skills and capacity as a designer, because you can design things that don't match your preferences, for specifications from other people, and so forth, and you will generally understand design better objectively.
Other Game design entries on this blog: Don't be Perfect! and Complexity Thresholds