The language may have a little to do with a sig like TidalWave was talking about.

A little harmless spamdexing.

I've been getting a few of the first example on my blog. While it looks harmless, they're actually spamdexing (a little bit of "black hat seo") by trying to associate their user account (and website links by extension) with the keywords in the blog (like Xander was saying, it's marketing). When you click on the link it counts as a positive hit from the blog. If a blog has enough hits positively for a key search their link will get a +1 bump up from the search engines in regard to relativity for the keywords. Most of the search engines have caught onto this and try to prevent it with relevance matching in their formulas.

The downside is if a user comes to your site for something off-topic because of this spam and leaves (bounces) the search engines will penalize your ranking overall (because of lack of substance) as well as your ranking for the page with the off-topic content. While there's not a lot to do with IT Security in spamdexing (unless they use an infected site as their own URL), it does impact the [social] performance of the site negatively overall if enough spammers do this and knock your site down in the rankings.

In regard to the second example it contains a hook for a two post spam operation (Commonly found in forums). The first poster will create an account and post a question that looks like a legitimate concern.

... Where else may I am getting that kind of information written in such an ideal means? ...

A short while later (within 20 minutes or so, up to even a couple of days) another poster (from the same country usually, if not the same IP range) will create a new account and post the answer, which contains the link in relevance to the original poster's question. Since most board moderators won't delete what looks like a real discussion, their spam fools someone again... it's still spamdexing though. A better-crafted marketing-style example might be:

I found a great resource for [keywords here] at [http://www.example.com/]. You should take a look since they have a lot of information related to [more keywords]. It should help you out.

Some of the other tricks they'll do is have a signature image that is a transparent GIF only 1 pixel by 1 pixel and wrapped in an <a> tag. This creates a link to some other website anywhere the poster has typed out their gibberish content. Just because you can't see it, doesn't mean it's not there.

Not so harmless Spam Threats impact Server Security

Some of the worst examples of spam will actually contain a link to an infected site, or they'll install a javascript keylogger. (I've seen the SVG hack used in signature lines to inject malicious script.) The keylogger is the one you'll need to watch-out for because they can capture the username and password of the blog/site admin or another user with elevated privileges when they try to log in (or any user creating an account) on the same page to delete the spam. Best case scenario, is if the user has enough access to see other users, the attacker will download the list of e-mail addresses from the users and send out spam e-mail messages to a market-targeted (marketing) list.

Innocent new users can have their credentials stolen, and since most people use the same passwords and the same e-mail address everywhere, now their accounts elsewhere can be compromised. (Facebook, LinkedIn, etc)

Worst case scenario, because most web developers of the CMS systems don't expect someone with "skillz" to get into the backend via one of these methods (trusted), they're not doing things like checking all of the admin forms for XSS or MySQL Injections (I've caught a few of my developers cutting corners in this method). From XSS to SQL injection it then depends on the security of the box, the limitations on the user accounts (don't run Apache as root), and the read/write access. Since they would be in the CMS you can assume that the user can likely write anything to the box they want. Delete the database, infect the site with a backdoor... now it's an IT security issue.