For a pure blackhat operation, it would simply be the newest competitor. Blackhatters rarely play the long game, they are used to burn-and-churn operations. They wouldn't have the patience to keep an unprofitable site running.

It's harder when it's a white-hat SEOer who is also comfortable wearing a blackhat-persona, they may have the patience and guile not to make it too evident. Because they know the long term payoff.

"When you report them for paid-links, you wouldn't use your real e-mail address, that doesn't make any sense."

And yet, using an email address that has zero previous visibility / fake-name generated looks suspicious too. Any thing where the sender is mostly anonymous is suspicious, particularly in answering the motive question. (Particularly silly would be using a free email provider, for example)

Again, Blackhatters aren't eager to put themselves on Google's radar, or any public spotlight. Only the naive ones use GMail / Analytics / Webmaster dashboard. They prefer operating behind the scenes and not drawing attention to themselves, because they have lots to hide.

It takes a bit of pre-planning, some good organisation, and a lot of patience to pull off a convincing online profile. Not really the hallmarks of the typical blackhatter.

Of course, if you're into identity theft, are you really willing to risk it ratting out a competitor. And you'll be in organised online crime territory

Plus the downside if the rest of the Blackhat community find out you've been snitching to Google. They may have loose morals and ethics when it comes to SEO, but they have some semblance of respect-earning.

None of this appeals to the blackhatter, seems an awfully contorted process to go through each time just to gain one ranking place (per competitor). Because it's a process that requires contacting a human at Google, it's also not something that's easily automatable or scriptable. Doesn't entirely fit the quick rinse and repeat / burn-n-churn of the typical Blackhatter.

Take out the scare-mongering of negative SEO, and examine what's left. Not much. In the wider picture, it won't even register a blip.

Now, the legal ramifications of someone being caught doing this. Motive and intent, destruction of business value, clear intent to deceive for financial gain. How many more elements are needed for this to be fraud?

Blackhatters may have loose morals or ethics, but they also know how to stay on the right side of the law. And also, not to drift too close towards the organised crime based operations.

Negative SEO won't be a regular tool for blackhat SEOers; too much risk, too much effort to pull off more than a handful of times without being spotted. Organised crime though, for extortion, most likely.

This doesn't scale without drawing attention to yourself.

It doesn't scale for an individual SEOer as a repeatable approach to ranking ahead of your competition. Most likely, it's mutually assured destruction - SEOers destroying each other, taking their clients with them.

It doesn't scale across the SEO industry. Too many people take this up as a tool, and the quality of Google search results suffer. That's when Google takes further action.

The one main way negative SEO back linking survives as a reusable technique is if it's used in small unnoticeable doses, and doesn't affect the typical Google user. Because when it does impact mainstream Google users, then Google takes the next step forward.

If the nightmare scenario materialises where SEOers destroy search quality results for mainstream users with negative SEO campaigns, Google flips the "spammy link penalty" off, all those sites affected bounce back immediately.

And then Google will comb through the data they've captured in that time period, and have an improved idea of what link sources are spammy. Google will have a much better idea of the network of sites you used (to benefit yourself before the penalty, and to negatively affect your competition during the penalty). It will stand out.

SEOers are in a classical prisoners dilemma.