There are more possibilities of link remove after some time from social bookmarking website because some social bookmarking websites are updating their listing after every three months or six months but i don't think the social bookmarking link will not show in link checker tool.
Post on some popular and high authority of bookmarking website for permanent listing because of low authentic website has been down after some time and you loose your backlink from that website. Social bookmarking are best to fast indexing of your website in search engine and directory are good to get permanent listing.
By bookmarking sites on a particular theme and tagging them with keywords, you can establish your expertise and make people follow you. From time to time, you can also add your own content.
Increases repeat visitors to your site - There are many people, who visit your website, and don't take any action on their first visit. But, if you can offer them bookmarking options on your page, they are sure to find your website again, which thereby increases the number of repeat visitors.
Provides information about your competitors - When somebody has bookmarked a site, then you only need to read it. So, it makes your work easier to know about all the competitor sites in your industry.
As mentioned above, there are a number of social bookmarking websites that are trusted by a lot. So, if you can have a link pointing to your website on their page, it means more visitors and higher ranking.
Bookmarking sites help save a lot of time and effort. In order to get targeted traffic to your website, you can use social bookmarking. It is an easy and absolutely free way to make your website popular.
Helps build backlinks for your website. You can build backlinks for your website through social bookmarking. Just ensure that you submit your website to bookmarking sites that feature do follow attribute. Thereby, you get quality backlinks to your website as well as you brand yourself too. Branding is important for successful online business.