I found this example sentence under the entry "sneaking" in Oxford Dictionary:
I've a sneaking suspicion they'll do well.
What puzzles me is what exactly the speaker is suspicious about. Literally, I can see it's a sentence without "that", which would make it to be like "I've a sneaking suspicion that they'll do well".
But that would also make the sentence's meaning tricky and sound unreasonable. If "they" will do well, then how could the speaker be suspicious? The speaker should wish people perform well, shouldn't he/she?
What is the correct interpretation of this tricky sentence?