To be clear, these statements aren't lies every time an employer says them. But they're inaccurate enough of the time that you shouldn't take them at face value when you hear them.
1. "We'll keep your résumé on file." This statement is often found in rejection letters, but what does it really mean? Job seekers usually assume that it means that they'll be kept in a database of candidates and contacted again if a promising opportunity opens up. In reality, it usually just means that their application materials will be filed away, not that they'll be looked at again in the future. In fact, every law-abiding employer keeps all the applications they receive on file, because the law requires them to store applications for a period of years before disposing of them. So this statement means little more than “we’ll comply with the law." Related to that...
2. "We'll let you know about future opportunities." If you're a very strong candidate and/or you had an unusual rapport with your interviewer, this might happen. More often, though, employers say this to candidates and then don't follow through. They might say it with the best of intentions and truly mean to follow through -- but when employers talk to hundreds, if not thousands of candidates a year, even the good ones can get quickly forgotten. What this means for job seekers is that you should never assume employers will reach back out to you when they have new openings; if you want to work for them, you should proactively check their listings and apply.
3. "We'll get back to you in two weeks." As most job seekers know from hard experience, interviewers' promises about timelines often end up being wildly wrong. What this statement really means is, "Off the top of my head, I'd think we should probably be able to move forward in a couple of weeks, if nothing else gets in the way. We'll get back to you if we want to talk further, but otherwise you might not hear anything."
4. "We'll let you know our decision either way." Interviewers often promise this but then don't follow through -- leaving legions of job candidates frustrated and anxious, wondering if they should move on or whether they'll ever get any post-interview closure.
5. "We were really impressed with you, but we had many qualified candidates." This might be true, but it's also routinely said even when it's not true. In fact, many companies include a statement like this in the form rejection letter that they send to everyone who applied and wasn't hired, and it's unlikely that they found every one of those people impressive. This is a nice way of cushioning rejection, nothing more, and job seekers shouldn't read anything into it.
6. "We have an amazing culture here." Employers love to talk up their cultures, but the truth is in the details: Do they allow flexible hours? Can you telecommute? What kind of professional development do they offer? How competitive are their salaries? Why do people leave? What are the internal politics like? Even companies that score badly on all these fronts like to talk up their culture in interviews -- so do your own research.
7. "We offer excellent benefits." For some reason, companies claim this -- and maybe even believe it -- even when their benefits aren't competitive with other companies in your field. Moreover, some companies offer generous vacation time on paper, but not in practice. If you can never get your time off approved and your manager frowns on taking vacations, it won't matter how much paid time off you're supposedly earning.
8. "They went with a candidate with more experience." Maybe they did and maybe they didn't, but this line is often a standard response given to candidates who ask why they didn't get the job. While it can certainly be true, it can also mean "we hated your personality" or "you talked too much in the interview."