Your mileage will vary on LinkedIn depending on the time you put into populating your profile.

I have written hundreds of profiles for clients this year - some clients are more concerned with branding (what does someone feel when they are directed to the profile or find it on their own) while others are much more concerned with just being discovered by recruiters, hiring managers, peers, etc. The approach is quite different, not unlike SEO techniques.

If you're getting good ads, chances are you put some time into your profile and added skills that help their recommendation algorithm.