Each bike I work on tells a story...how the owner cares, or doesn't, for it...if any 'customizations' have been done to it...the condition...how long, or not, parts last and still work often with no/little care and maintenance...etc.
I've been a 'wrench monkey' in several shops and states for over 30 years and still enjoy working on bikes...I'm 70 and still work as a part time wrench...working 15 hours per week.