Relevant Reciprocal Link Trading Information:

This tool allows to see if link partners are still linking back at your site. This is not 100% accurate, but it has worked pretty well on a number of tests.

Most reciprocal link requests are complete garbage, and most spammy reciprocal links probably do not help sites out that much in Google's search results.

Generally if you can afford a decent marketing budget its not recommend trading links with anyone who you trusted so little that you felt you had to frequently check up on them. Instead of trying to develop link partnerships it may be better building friendships or business partnerships.