That's only because they never make a cogent argument, supported by links, in their posts. If they did so I would cut them a lot more slack and they might actually convince me that they are right. I don't have a closed mind. Meantime, the preponderance of evidence is firmly against these people. Science deniers are not cool people.
You no doubt have noticed that I reserve my most vitriolic language for their misinformation and lies. I don't attack anybody personally, just their opinions and especially when they refuse to post credible links. Did I mention that failure to post credible links is what triggers me the most? Such people waste out time and I don't understand why they (apparently) aren't given more time off the forum.