If you were given 5 cards with each of the following occupations, professions written on each card, do you?

think you could correctly match the occupation to the person who holds the position, and why or why not?

1. Doctor
2. Mechanic
3. Homicide Detective
4. Nurse
5. Car Salesperson

They are all wearing a white shirt or blouse and jeans.

possibly but it would be based on preconceptions that i currently hold, how i would attempt to determine such si as follows, but understand that the traits i am attributing to each is not universal
doctors are arrogant and would hold them self as such also their hands would be smooth w manicured nails possibly, also would most likely be older
mechanic would be bigger, stronger, wirey, have dirty hands possibly and unclean nails
homicide detective would be interested in surveying their surroundings to determine all aspects of the situation
nurse would possibly be more relaxed and have a compassionate look
car salesperson would also be arrogant, possibly a bit nervous, would be personable

it would be easier to determine their jobs by conserving with them
and as i indicated these traits i subscribed to them are not universal, a doctor could have dirty hands and be burly, a detective appear disinterested etc

no i couldn't

Yes, no problem.

the mechanic would be easy - he'd have grease stained hands [i would know], the rest seem like they're possible to figure out - but the doctor and nurse would prolly be the hardest, eh?