I've heard the following advice blog posts (e.g. https://www.kalzumeus.com/2012/01/23/salary-negotiation/) about job interviews (my paraphrase):
As a job applicant, you should not reveal any kind of salary requirement or expectation. The potential employer has to offer you a salary, and if they don't, insist on it as hard as you can, even threatening not to accept the potential job offer.
The reasoning behind this advice is that once the employer is close to offering you a job, they have invested too much into getting you on board that they will not turn around this late just because they want to hear the applicant's salary expectation first. So they'll offer what they can reasonably pay, and will not try to bargain much. In contrast, if the applicant reveals their salary expectation, they will usually account for some room for negotiation, and thus the employer will haggle.
(Side note: The same advice would usually apply for previous salaries, not only for salary expectations. For example, I've been told to disclose my current salary by a head hunter, claiming that this is industry standard. See Is it wise to release your current income if what you expected is twice as high as your current salary?)
I'm wondering whether this advice is good. In most of my applications during my professional life, I've tried to follow it half-heartedly. Always, the employer or head hunter asked upfront, or very early. Trying to decline to answer would usually not be accepted. In one case, the HR person told me that I would not see the next round if I didn't answer the question. So I did eventually. Should I really insist harder? Is this really HR & head hunters trying to barter me down? Or will that make stand out as a really goofy candidate?
Probably, this is related to the industry and the region, so let's say IT in Germany (or Europe).