I think it really depends on your blog, the market and what you want to achieve.  A tight niche could be very lucrative if you become the authority.

Say a keyword has approx 100 searches per month and you rank well and achieve a sale/signup/commitment per month from that.  Then there are 30 other search terms with similar volumes you can rank for.  Is this valuable to you?

If you are selling 'blue widgets' at £1 per widget and a typical customer only ever buys one or two then your niche blog may not be worth your efforts.  But if they are repeat purchasers then again that changes the landscape.

Name, Address, Phone - you should provide comprehensive contact details.  Part of your service could/should be to double check their details on their site and make sure it identically matches on your listing.  Businesses are still lapse in this, or try to extend their address to capture more than one county, as if it will somehow do them good.

They also need to give you fresh new content about themselves, not some default directory description.

True!  

I'm working on a site that had a very poor disavow file in place from a previous agency.  I went through the link profile with a fine tooth comb and added a bunch more domains to the file.  Organic traffic has gone up over 80%.

That is not our only problem and there are other factors to work on but the cleansing is reassuring even though we know the profile is pretty thin.  But again that just goes to show quality always wins over quantity.

I would say there may be a whole host of issues hampering ranking but a dirty profile is a must fix, no matter the immediate outcome.  I explain to clients that I anticipate a short term fall and why to set their expectations, then anything positive is a great bonus.

For me longtail keywords are purely more finely focused keywords cascaded down from the big money/focus keywords whatever they may be.  So it doesn't matter if they are model related or how any words etc, they are just one way or another the closest thing you can get to a finer granularity exact match the next level from the big volume main keyword.  I think the target is selecting the ones with modest competition and a search volume.

Has the mobile/skype link been set up incorrectly, not using the attribute?  I'd check the source code to see what the link actually is.  It should be something like -

Stripping it back to the bone the basic rule is that you violate Google terms by purchasing links.  It is not an instant Google hit if you do, but you kind of move into death row and take your chance.

Because you don't always instantly suffer a penalty doesn't mean that you should follow any advice that seems like a quick fix.  I would stick to here or the other main marketing sites to get a concrete base of what is ethical, what works and what doesn't.  That's not to suggest you shouldn't implement your own strategies but they should be built on that concrete base.

I think the most important aspect of your question is to not trust a tool.  The tool might flag domains/URLs as spam or manipulated links but the most important thing is to manually inspect each domain.  I have had reports from tools where the domain in question is actually not a problem at all when inspected.

If you are getting 404, 403 or 503 error messages the links are gone.  You wouldn't be penalised by Google for these because they no longer exist.  There is no need to disavow because they don't exist, but you wouldn't be causing a problem if you did.  The potential issue is that those header responses 'could' change back to a 200 found.  I'd be inclined to monitor them at this stage and add to the disavow if the status changes.  A 503 header is a maintenance response so that may come back and you would want to check what you'd be disavowing, as the link may be good.

With regard to disavowing all the links.  If you have a toxic link profile you have an issue you need to address and resolve as quickly as you can, so if you determine there are 100 toxic links/domains you will want to add them to the disavow in one hit and hope that you have captured them all.

But please be aware that if some of the links are just a bit spammy/low quality then Google looks like it takes the view to ignore those links anyway.

Some things you need to manually check are:

• the relevance of the link
• the quality of the content
• the anchor text (e.g. have you got exact match, close match anchor on multiple dubious quality posts)
• the ranking of the page/domain
• the placement of the link on the page (e.g. is is a site-wide footer link).
• the quality throughout the domain
• is the link paid for but dofollow (e.g. are there signs on the site that content can be somehow 'purchased', advertorial)

yes, if the date of the cache is prior.  So I would suggest disabling javascript in the browser reload the page and see if the expected text is displayed.  If not that's what Google misses.

...and yes Google should show all the text in the cache version (text only) if the cached version is subsequent to your amendment.

"Other SEO's have never had a problem with this arrangement, but this SEO claimed what they do is secret and for no one else to see."

Run a mile!!!

The right format means ensuring everywhere online that your business appears the address is identical.  The same goes for the telephone number.

So for example

Acme Ltd
Some Street
Bigtown
AB1 XYZ

is not the same as

Acme Ltd
Unit 1
Some Street
Bigtown
District
AB1 XYZ

or

Acme;
Some Street;
District;
AB1 XYZ

How that is coded into the html is not so important as long as the text is crawl-able and presented in an address format.