I think this is caused by a cognitive bias. The more positive things about company X we hear that matter to us, the more we view anything they do in a positive

I think this is caused by a cognitive bias. The more positive things about company X we hear that matter to us, the more we view anything they do in a positive light and the less weight we give to anything that counteracts that belief. Conversely, the more negative things about company X we hear that matter to us, the more we view anything they do in a negative light and the less weight we give to anything that counteracts that belief. Once a trend starts, it gets harder and harder to change people's minds.