In the race to acquire better site ranking and so also the visitors the bloggers just grab every opportunity to put their link on other blogs.So spam other bloggers comment section,some do link exchange.So what if the site has a bad reputation nobody cares is the reality.So think before you link with others or try link exchange through the following checklist:
1.Is the blog already has too many links exchanged with others.
2.Does the content of the blog suites yours to go forward with link exchange.
3.Whether the blog has a bad reputation over the blogosphere and linking with that blog might just not even my readers away.
4.Whether providing that blogs link might help my readers understand the point better.
If you get all the negative response after these points into consideration then better no to go ahead in link building .Else you are free to get into link sharing.