That sounds like the textbook definition of a Relevant Link. Client makes mechanical parts, sells to mining & construction industry, links to/from mining & construction industry... not sure what would make that irrelevant. Google won't penalize you for those.

Its like how a Square is a Square but also Rhombus and a Rectangle. Long tail keywords can be any and all of those definitions depending on the moment, your goals and your needs.

In most cases I wouldn't consider a Low Traffic term a "Long Tail Keyword" simply because it has low traffic. But I would argue that Long Tail Keywords are likely to have lower traffic than their short tail counterparts. People are more likely to search using shorter terms and phrases but sometimes a 4+ word combination can be popular. But I would argue that a Long Tail Keyword/term/phrase is likely to be 3, 4, 5+ words long. Can those words be all extremely product specific? Sure. Do they need to be? No. Are they more specific than a one or two word short tail phrase? Yes.

One word with low traffic is probably just a bad keyword to be using. A 4 word phrase with high traffic could just be a popular long tail search. In some cases it will depend on your industry. Some phrases can have multiple meanings. Just because a 4 word phrase has good traffic doesn't mean you need to use it if the first 3 pages in the SERPs are all sites devoted to a completely different concept that happens to have the same phrasing.

Ha, okay... you got me there. I just figured the "official" google stance would be important to state. If someone really wanted to they could nicely ask for reviews and just happen to also slide a few something or other the way of the reviewer. Though i personally would not endorse that. But yes, he could invite reviewers, give them an "industry rate" on rooms, happen to state that reviews of both a positive or negative stance are greatly appreciated as it allows the hotel to work on improving weakness and help evaluate what the current strengths are, etc. etc. Its all in how you word it and present it.

As per the Google Places reviews guidelines (link

Conflict of interest: Reviews are only valuable when they are honest and unbiased. For instance, as a business owner or employee you should not review your own business or current place of work. Don’t offer money or product to others to write reviews for your business or write negative reviews about a competitor. We also discourage specialized review stations or kiosks set up at your place of business for the sole purpose of soliciting reviews. As a reviewer, you should not accept money or product from a business to write a review about them. Additionally, don’t feel compelled to review a certain way just because an employee of that business asked you to do so. Finally, don’t post reviews on behalf of others or misrepresent your identity or affiliation with the place you are reviewing.

So I'd suggest not offering free visits in exchange for trying to get reviews (positive or negative).