I mostly agree -- comments are not proof that the coder understood the problem (although it may be evidence he or she did NOT); instead, comments are an effort by the coder to lift up the next coder who has to maintain, fix, extend or test the code. I think of comments as time-saving work: you are doing a few minutes (or hours) work now, to save Future You (who may wear a different face) from spending hours (or days) and costing your company a lot of money.
However, when you are faced with a block of code you don't understand (whether you wrote it or not), and a block of comments, it's going to be hard to trust that block of comments if it's filled with grammatical or spelling errors.