Not really. You could use a batch process to copy the bookmarks to another PDF and then run spell check. Here is the documentation link to the sample batch sequences that can do this: http://www.adobe.com/devnet/acrobat/pdfs/batch_sequences.pdf
You might also check some of these third party bookmark products but it didn't look as though they offered spell checking. http://www.acrobatusers.com/articles/2007/02/bookmark_options/
Lori Kassuba is an AUC Expert and Community Manager for AcrobatUsers.com.
The ability to spelcheck bookmarks would be a really handy feature. I often prepare PDF's of medical records and other technical materials and end up with lots of bookmarks, many of which have complex spellings. I hate it when I get one all done up and sent out to my clients and then discover misspellings in the bookmarks.