I second this warning (although I confess I didn't know that people were offering organized bitcointalk thread bumping services; I thought it was always just random members looking to make a few bucks).
It's very well organized, and the one that has monopoly here on bitcointalk is
Vitor Services. Per my guesstimate they are responsible for at least 80%+ of all thread bumping that is going on. I've been playing whack-a-mole game with them for quite some time (not so much lately) and it seems to me that they have unlimited amount of old newbie accounts made years ago, that they activate once the ones they are using get banned/tagged.
One would think that kind of "marketing technique" would die after bumping changes, but they are still alive and kicking as in the last ~year and a half we identified more than 120
ANN threads that are using bumping services while real number is probably much higher. That reminds me, I have to update the list as I found several more threads where thread bumping is going on as we speak.
You can probably tell pretty quickly whether a conversation is "organic" or not simply by looking at the ranks, registration dates, post histories, and even usernames of the members having said conversation. The idiots who do crap like that don't tend to be stealthy, and they're easy to spot by mods, older forum members, or anyone else who's frequented the ANN section for a while.
Yep, it's pretty much obvious to everyone that those conversations are not organic at all. They usually use newbie accounts, write one liners, or ask some stupid question and then they wait OP to answer. Rinse and repeat. I suspect that there is one high-end group doing the same but in a way less conspicuous way and using higher rank accounts, so it's much harder to connect all the dots.
But there is some poetic justice in all of this, those that are trying to scam investors are getting scammed by those "marketing agencies", selling them something that doesn't work.