Too many are so ideologically minded that they just spew what each group says. There is no search for what's true. It doesn't matter if the dishonesty is revealed because winning is more important.
That's true in two ways. One way has to do with the individual. Psychologically, we have a capacity to act rationally, but also a capacity to act on emotions. So, ideologically minded people can choose to engage in group think, put their emotional reactions above reason and refuse to see dishonesty.
But each individual will also control his behavior to some degree in reaction to the culture as a whole. If the culture strongly opposes a given set of beliefs, there will be far fewer public supporters of those beliefs. They will be less assertive. (And there will be fewer people to hold those beliefs.) An example here is an individual who is actually a racist - like a KKK member. He feels constrained to hide his beliefs to a much greater degree now than in the fifties. And there are fewer people who have chosen to be members of the KKK now than in the past. This is just saying that individuals will react to the culture, and not just to an ideology by itself.
The second way is about the group, rather than the individual, and in which each group is empowered - to some degree or another - by the culture it is in. A culture is a whole set of beliefs that have evolved such as to co-exist in a society at a given point of time. When a group holds beliefs that held by, say, 90 plus percent of the people in the society, as for example, Christianity was in America a couple hundred years ago, there will be very little motivation, and very few incidents that arise that put those beliefs in question. And the fact that there will be far, far less conflict means that there will be less dishonesty. Christianity was as wrong in its belief systems back then as it is now, but now there are dishonest efforts to defend it and dishonest efforts to attack it. Partisanship is just the obvious result of actual conflict. You don't get one belief system replacing another without a lot of conflict at the point where the balance of power is close to changing. (Cultural Marxism has been about changing nearly all the belief systems of the culture as a necessay pre-condition to getting democratic acceptance of Marxism politically).
There are two aspects that are worth looking at: Some things should be viewed as existing over a spectrum instead of as being binary, and things can change over time.
1.) The degree of rationality versus emotionalism in any given individual (on any given issue, at any given time) is a thing that should be viewed as "to what degree" because some very ideological people have gone from one side of an argument (over years, usually) to another. Christopher Hitchens was a Christian, then a Communist, then a Conservative.
2.) Our culture evolves over time. We learn new facts, establish new theories, and react to these new things. As individuals exercise their rational faculties (or fail to), they form their ideas and in this fashion our culture evolves over time. If we allow ourselves to become too disheartened or cynical over the fact that people often put group partisanship ahead of honesty, then we will have no way to understand changes for the better, or find the motivation to participate in positive changes. When we understand that people are capable of choosing in favor of a more rational position, it encourages us to find better arguments (or, at the least, to get better at discriminating between those who are so willingly dishonest as be a waste of time from those who aren't).
Lastly, this all sums up the importance of restoring rationality to the educational systems - the schools. As long as progressives control them, the ability to teach the young to think critically is lost and we end up with more people who are so partisan that they are willing to be dishonest in support of their ideology.