I've been looking for a job. A few companies/recruiters have contacted me asking if would come in for an interview (<i>I didn't apply</i>). I'm reasonably sure that I would not accept an offer from them (due to company size, the company's product/market, and/or the company's brand), even if they gave me one. On the other hand, some engineers I've spoken to have said that their initial judgment of a company was proven wrong or changed when they actually interviewed.<p>That being said, should I (ethically) take interviews just for 1) practice, 2) leverage with the companies I actually want, and/or 3) the possibility of being pleasantly surprised, or should I just decline and not waste their time?
Back before I became a consultant after about 2-3 years at whatever my current job was I'd start taking a couple interviews every 6 months. This allowed me to gauge the market for what skill sets/tools were being used in my area and also what salaries are offered. I never considered using this information as leverage though, I just left when I got a better or more interesting job offer. Now I consult so I am interviewing every 6-18 months anyways.
I would say if they're a large company you can, since you're wasting a pathetically small amount of their cycles. If they're a small startup I would say that it is less conscionable as the impact of taking time to talk to you is significantly higher. The leverage bit can't hurt, after all they want to have leverage over you; at core it's a business arrangement and no one should have their feelings hurt over treating it as such.
Some advice I got was to go for an interview every 6 to 8 months whether you are looking for a job or not. The skill of interviewing well is different to the skill of actually doing the job and it never hurts to stay in practice.
Do you currently have a job? You have to usually waste a day traveling or going to their site. Many times interviews are very poorly organized. I think unless you have a definite end goal it is waste of time.