Comments like "add one to index" are a symptom of laziness, not of commenting about the wrong thing. As an example, here is some of my actual code:

    /* Prompt for scheduler. */
    if (!flag_scheduler_selected && !flag_no_prompts) {
        option_scheduler = prompt_scheduler();
    }

The purpose of the comment is not to tell you what it is doing or why I'm doing it. The comment is there to tell you that what I am doing now has nothing to do with what came before. It signals a mental context switch. Without the comment, you wouldn't be able to easily scan the code and see where different things are happening.