Pretty unlikely. Most classified links are nofollow, js, or simply low quality.

Increasingly, these days, it's not the number of links, but the quality that counts.

Hi again Quadrille. So what about the negative effects?

Using these free ads to create 1000´s of ads that can target your keywords could maybe be seen as Spamming (by the search engines) and penalise that site do such activity, what do you think?

Certainly possible; but I reckon the experiment would not justify the effort of trying it.

Go for quality. You'll never have to worry about that. I have sites with fewer than 10 links that consistently do much, much better than sites I know to have thousands of cr*p links. All that effort, no reward, and occasionally a bad neighborhood penalty.

I can't see the attraction!

I used to work for a company - si one of their sites was Google banned because they advertised it in CraigList... So think twice

The thing is I see so many companies doing this and all my SEO has gone to pot as these free advertisers posts are getting higher positioning. I´m really thinking about joining these cowboys, however, I see it degrading to the services my company offers. I have tried a few posts in recent and have got a CTR much better than adwords... for free...

The banning question is a big worry. Anyone know of anymore stories?

Sure I have more stories, but IMHO, this is a more useful response: When you play in that realm, the story is pretty simple. That approach carries greater risk than does marketing in more "Search Engine Acceptable" ways.

You may or may not make more money going that route. Your chances of being penalized or banned go up.

There are no hard and fast rules or guarantees, which is what so many people seem to want. The simple fact is, this is what business is all about: Risk/Reward/ROI.

Or you can choose:

plain old fashioned hard work / little or no risk / roi / luck.

But i agree that the choice is yours; certainly the higher the risk, the greater the potential reward - but even those who get such rewards, often do not get them for long.

While those who slog patiently away, taking a long-term view, often do very well indeed, and probably sleep much better.

Don't feel the need to do anything just because your rivals do - especially if you cannot be sure what it is they are doing right. They may be thriving despite minor spamming, not because of it.

Your choice ;)