I think I find a bike, or bike part, lustworthy when it blends art, form and function - or maybe a better way of saying it, "an artful blend of form and function" .

That's why beautifully sculpted lugs (like Vanilla's), exquisite paint jobs (Colnago, Lynskey), Phil Wood hubs, Nitto handlebars and stems, etc, etc. are all so lustworthy to me - all are examples of craftsmanship and attention to detail that have turned ordinary things into art.