Your advice is correct, but depressing. These body-language games people play with each other are manipulative, and sometimes deceptive. Even if there's truth behind the assertion of confidence, the assertion was made to manipulate the outcome.
No doubt, the most obvious rebuttal is that the interviewer will be doing their best to manipulate no matter your tactic, so you either circumvent them or acquiesce to them.
I take "manipulation" to be somewhat similar to "lying." The distinction is intent. So, you have at least three scenarios:
- 1) You earnestly express a belief, and it happens to have the desired outcome.
- 2) You express a belief primarily because you know what outcome it will create.
- 3) And the grey area: You honestly hold a belief, but you're also well informed about how that belief must be presented to modify your outcome.
Realistically, most of us live in that third option. The distinction between a job interview, and say, a dinner out with a friend, is that you're highly incentivized during a job interview to present yourself in the best light possible. Most of us are aware of how we'll come off when we make a statement, and there's always some incentive to come off in a better light. But, a job interview generally removes the possibility for blunt honesty. "Well, of course I'm excited to work here. If I don't express that excitement, you won't hire me!" Such a frank appraisal isn't really possible in a job interview. But in another (ie, a social) context, you could make a sarcastic quip, or even just an honest appraisal of the situation. "I'm excited to see you, but being in this crowded restaurant is giving me a bit of a panic attack." Maybe that's not the best social tact, but the option is much more available in a social context.
I'm meandering a bit here, but I hope my point comes through. When we're stuck in that grey area of option #3 in most situations in every day life, we can generally chose to go with honesty if we prefer. In a job interview, our success and survival depends on forcing us toward option #2.
Lying, manipulation, and violence share the same underlying theme: depriving someone else of their free choice. Either by withholding truth, playing on their subconsciousness, or threatening harm.
No doubt, the most obvious rebuttal is that the interviewer will be doing their best to manipulate no matter your tactic, so you either circumvent them or acquiesce to them.