how do you judge imagination? that is, how am I to know that my imagination is more or less vivid than the next persons? how do you go about judging? if you ask me to imagine something (especially something more complicated), how can you know how clear/accurate my image is?

also, and I've asked this many times before, but must not have got a satisfactory answer - how does one imagine a taste or a smell? doesn't imagine imply images? after all, it is in the name. should there be new words for "imagining" tastes, sounds, smells, sensations (touch)?