so we can post link when commenting in some subs right???

which subs accept this rule

so i can spam

Not really, you have to do it slyly when spamming reddit. Best thing is to post informative content and boost the post with upvotes so it goes under the mods radar. However, it's still not guaranteed the post will stay up.

Some people post something informative, wait a few days and then re-edit their post to include the link, I'm not sure how good that is, but you can try it out.

Depends on the sub rules and what your link is about.

If you're going to randomly drop affiliate or CPA links to any subreddit, then this will not go a long way.

A good way to get a feeling of what links you can post: check what kind of links are most of the time shared by other posters in a given subreddit.