it seems that google deals with both issues differently i think?? so, which is more ugly buying or selling links?
selling links of course. any link that u buy at worst contributes zero to your rankings, but selling links will drag it down.
Selling, of course. They'll hit the sellers hard, which by default hits the buyers as well. For them it's like killing two birds with one stone. The seller gets banned (or penalized) and the buyers get their rank-influencing links devalued.
Google totally dislike trading link, its two person involved buyer as well seller when seller will punished it may buyer also so better if you avoid by this
You say, selling links has punishment by google? have you ever seen any punishment till now? and there are a lot of websites with high Pr that offering link on their site , so you say it is illegal ?
There are a lot of websites who do sell links, and there have been a fair number of them who have been penalised by Google.