i belive this has been covered before.
what the other guys have said is correct.
since i've done this a little bit and discused it w/ other tool fools i'll toss in my 2 pecos.
it depends on the tool and what you want to do w/ it.
if you find old hand tools and just want to flip 'em i'd say leave 'em as is.
for the time you put into 'em(wire wheel/buff/polish) you wont get that back. guys buying old/vintage stuff want it orig to clean themself or leave as is. ive been sick of the word PATINA for about 15 years, but some guys like that ****

multiple part tools like ratchets and adjustable you can spend a little time, cleaning 'em up but not rebuilding/restoring if you plan on selling.
bigger ticket items like tool boxes and drill presses and vises and lathes or larger tools is getting into tougher territory.
like rebuilding/restoring a car. you can(maybe) make some $ on your initial investment and parts/materials(maybe) but you will lose on your labor/time spent.
you gotta think what your "time" is worth.
depending on the task i'd want $20 to $40 per hour for me to make/do something.
i'm not gonna spend 3 hours making a bracket that i can buy for 15 bucks...unless its something custom i just gotta do myself.
on the other hand, if you want to keep a small or large tool for yourself than you have 2 options, in my opinion.....
1) make it clean and functional and use the **** out of it.
2) go full on, full tilt and make it look like it just rolled off the showroom floor or better........but than you'll feel bad using it
i guess what i'm getting at is if its just for yourself and it makes you happy, do it.
if its a hobby dont waste yer time polishing a wrench you got for 50 cents and try to sell it for 5 bucks(there are exceptions). we know better.
damn, sorry i rambled on guys. i've been drinking
