Let's take a step back.  In theory, all advertising and marketing communications that don't belong in their placements are ineffective.  Good messaging organically fits the dynamic in which it is delivered.

The ethicacy (and possible legality) of sponsored posts that fit is a matter of great debate.

But the value of sponsored posts that have do not fit is a joke.  These posts will not perform for the marketer and will diminish the value of the blog and the blogger to their audience.

With that in mind, where does SocialSpark fit?  Firstly, SocialSpark vets their bloggers and has set some guidelines for participation.  Some of their publically available criteria are listed below:

• Blogs submitted to the marketplace may not include or support: excessive profanity, violence, or racial intolerance, illicit drugs or drug paraphernalia, pornography, adult or mature content, or any other content that promotes intolerance, illegal activity, or infringes on the legal rights of others.
• Minimum Blog Age. Blogs must be live for a minimum of ninety (90) days, counted from the date of the blog's first post, with at least twenty (20) pre-existing posts written in the 90 days prior to registration with the SocialSpark Marketplace.
• You may post a maximum of three (3) SocialSpark Marketplace Opportunity-related posts per blog in any given day. SocialSpark posts may not appear consecutively on your blog. Each SocialSpark post must be immediately preceded and immediately followed by at least one non-sponsored, original content post. The prohibition on consecutive 'sponsored' posts apply to both SocialSpark Direct and Marketplace Opportunities, as well as other sponsored posts from competitive services.
• Interim Posts. Your last non Opportunity-related post must have been within the seven (7) days immediately preceding your Opportunity-related post. After any break in blog activity of seven plus (7+) days, interim posts, that is, posts between Opportunity-related posts, submitted on the same day as your paid Opportunity-related posts will not count towards this requirement.
• Private Posts. Interim posts must not be labeled "Private" or locked out. Interim posts must also be of a reasonable length, at least one (1) paragraph, three (3) to five (5) sentences. If your blog's interim posts lack quality SocialSpark may terminate your account.

So SocialSpark has some quality control.  But does quality control deliver "fits like a glove" integration?

Are SocialSpark's guidelines enough to ensure a good quality fit?  That's for you as a marketer to decide.  But remember, sponsored posts that do not fit do not deliver.

My litmus test: ask yourself, will this generate any value for anyone in the long term?  If the answer is no, it's spam.  If the answer is Yes, but it's evil, then you're probably too focused on buying your success versus building it appropriately.  Stop chasing shortcuts and start earning your place in the conversation.

Recommended Reads
Blog Council on Disclosure
WOMMA on Ethics
Izea's proposed Universal Disclosure manifesto
Andy Sernovitz's Comments and Disclosure Policy (oldie but a favorite)
Lively debate in the comments on TechCrunch - I really hope that whatever agency or communications lead partnered with Commission Junction on these efforts did their homework before writing that PO. I'd hate to be on the other end of that call tomorrow.