There is always that possibility, yes. Still, most people basically just believe whatever it is that they want to believe...and they only search out the facts which support their belief. That's how the human mind functions.

You can usually find some facts which appear to support either side of any given argument, and you can easily ignore those that don't...or just reason your way around them somehow. That is exactly what people generally do.

I'm not saying there isn't an ultimate and final truth. There always is. Sometimes it's a mixed truth...that is to say, both sides can be partly right and partly wrong. But it's not the truth that people are really after. What they are after is to "win" the confrontation. They may think they're after the truth, they may believe it with all assurance, but what they are truly after is victory over their opponent(s).