"Valid criticism" refers to feedback or an opinion that is reasonable, well-founded, and justifiable. It is constructive feedback that highlights areas for improvement or flaws based on logical reasoning or evidence. Full definition
Second, you point out the social structural critique of evolutionary psychology, which I feel is a perfectly valid criticism of the theory and something that should not be dismissed. (scienceofrelationships.com)
This is the most valid criticism I personally have of the diet, as the best diet plan is the one you actually stick with and follow through on! (nerdfitness.com)
A great many criticisms of the Christian Faith, as has already been suggested, are not valid criticisms at all. (religion-online.org)