What is the attitude of social networks to user advertising on their sites?

Question

Computer networks

Hello,
with social networks, users create various content. If, along with the content (photos and text), the user places advertising links in each post, will the social media themselves. networks to block such activity?
I've only seen custom ads on LiveJournal, but there bloggers make separate posts with the captions "Advertisement", plus some magazines are decorated with advertising pictures.
If there are examples of communities with advertising links, then I will be grateful for links to them (preferably in private messages). I want to see how they are designed and what they want for advertising.
Interested to begin with such networks as "VKontakte", "Facebook", "Twitter", "LiveJournal" and "Odnoklassniki".

Answer 1

Any community or public is by and large advertising, attracting users to your product.
vk.com/datahaven
vk.com/xakep_mag
what is this if not an advertisement, if your friend asks you for an opinion, (what kind of razor do you use) you say a vest, what is it? Advertising.

Answer 2

they are quite loyal if there are no complaints about such a user.
and about prices, you can contact the administration of any more or less "live" community and ask for a quote.