How to politely point out an issue with a cited paper? I am writing a paper that illustrates a technique that is superior to a technique presented in a separate paper that I am citing as part of my work. The technique in the prior paper is not wrong, but it has several major drawbacks that my results address.

My question is, what is a polite way to point out the problems in the initial results, and then demonstrate why my results address these problems without coming across as insulting to the original authors? I would prefer an explanation of how to actually point out their drawbacks, rather than one that avoids it altogether, because I think it allows me to give a more clear and cohesive explanation of my findings. For example, I would prefer not to resort to just saying, "My technique is , which has ,  and  advantages", because I think that pointing out drawbacks of earlier techniques will highlight and clarify the advantages of this new technique.

I would fully expect (and hope) that someone in the future would come along and point out the drawbacks of my approach, and how they improved upon it. It just seems to me that if I don't point out the drawbacks in the previous approach, I'm being both intellectually dishonest, and unfair to the reader who would have gained a deeper understanding of my paper had they had the full context.
I think, the principle

Show, don't tell.

applies and suffices. You don't need to point out flaws and drawbacks, you just show the points where you made improvements. State facts, back them up, avoid opinionated statements and you should be fine. This way "being polite" is not necessary, since you will not come near some "impolite" statement.