The “dirty little secret” about full-text search indexes is that they don’t help with ‘%blabla%’ predicates.
Well, it’s not a secret, it’s right there in the documentation.
A lot of us get the impression that full-text search is designed to handle “full wildcard” searches, probably just because of the name. “Full-Text Searches” sounds like it means “All The Searches”. But that’s not actually what it means.
Kendra’s take is a bit more optimistic than mine; I’m definitely more inclined to dump text out to a Lucene-based indexing system (like Solr or ElasticSearch), as they’ll typically perform faster and solve problems that full-text cannot. Some of that may just be that I was never very good at full-text indexing, though.