I know what you mean. I think some people has misunderstood your post. Do you mean its a smell which isnt actually there but you think you can smell it and then goes quickly. I get the ammonia one now and again.

It is proberly your brain playing tricks on you. I mean your brain is the part of your body which actually lets you know what the smell is after it has entered your nose. So if it has smelt that smell before, I would think it would have a chemical pre disposition to recreate that smell even though it isnt there. Then again I could just be talking shit :thumbsup: