A website receiving nothing but dofollow backlinks is going to look very unnatural to search engines. Far better to leave good high-quality comments on niche-relevant blogs without concerning yourself about whether or not they will be dofollow.

Search engines expect and reward backlinks that appear to have evolved naturally, and nothing but dofollow is hardly going to fit that criteria.

DoFollow blogs are hard to find. Sometimes you'll find small lists shared here. But I never really understand why. All of the blogs are hammered by careless marketers and they usually end up making comments NoFollow.

I can't really understand your question, but based on other people's replies I'll do my best to help. A nofollow blog attaches HTML to OBL that tells search engines not to weigh the link in terms of link juice. It's hard to say how effective this is, but the basic idea is that the link won't count for ratings. Dofollow is just the absense of the nofollow HTML and when a crawler crawls a blog and finds the link, it will carry weight in SERPs.

If you are looking for a good way to find dofollow blogs check out Comment Kahuna. It is a free piece of software that finds blogs related to a keyword and can sort out nofollow and dofollow. Though dofollow is good for rankings, don't ignore nofollow because you can generate traffic just from people clicking the link.

how to copy and extract the search result from Comment Kahuna to a text file ?