[quote=@pyroman]
So, obviously with techno-organic bots like Blackarachnia and Sklog, they have some sort of pain receptors due to their semi-organic nature, but I've always wondered about normal bots and such. I've always just thought of the metaphysical spark being able to somehow allow solid metals and stuff too feel using science-magic. 
[/quote]

I don't think there has ever been an official explanation how Transformers "feel" so its best to roll with your own interpretation. 

All we know is that they go "ow" like we do if they are damaged from an attack. We can feel pain because of our nervous system and the many nervous receptors (or in this case, nociceptors) that create and send impulses to our brains, informing us of what we are feeling and how severe it is. 

I [i]imagine[/i] most Transformers sharing a similar concept. However, it is evident that they clearly have incredible tolerance to the aftermath of any damage taken or they simply don't register much at all unless there is plenty of internal damage sustained that can critically effect how they function afterwards. I'm pretty sure most of us have seen more than one Transformer cartoon and seen a character not complaining (in pain) that their arm was blown off and sees damage as an unfortunate happenstance.

EDIT: I rather not get too involved with the Spark concept as there are many branching continuities that describe its overall involvement in different ways. The general gist I see is that the Spark is literally the physically manifestation of a Transformer's soul and a body cannot survive without it (though there are a few weird cases where that is not quite true to an extent).

EDIT 2: My grammar this evening sucks so badly, I've re-edited this post multiple times already.