That can be true, especially for objective facts, but I would expect such criticism to be biased to the point of unreliability - "We taste better than x (according to our staff)", "we have higher quality than x (at double the price)", "we’re like x but cheaper (and we have nearly 20% of their features)". And even then, as an input there can be value, but it's helpful to at least know that it's coming from a competitor so I can anticipate the bias.