Hmm, I don't know how I should word this, nor would I say that I fully understand what you mean, could you expand on this?
Spending an output doesn't necessarily require a signature. What it does require is an unlocking script, which contains a signature 99.9% of the time, but not always. An example is the unlocking script for each address in this thread:
REWARD offered for hash collisions for SHA1, SHA256, RIPEMD160 and other. To spend from address - 35Snmmy3uhaer2gTboc81ayCip4m9DT4ko - you "only" need to find an SHA256 collision; if you do, you can construct an unlocking script and claim the reward, i.e. spend the input without a signature.