Should the guilty always be made to pay for their crimes?

I think it depends on the crime. When it comes down to it, we're all guilty of something and most of us don't answer for many "crimes". I don't see why some illegal crimes should be treated any differently in an imperfect world.

I worry that exceptions could unravel the whole thing.

Yes, in some way or another

It all depends on the crime

No.

There are exceptions to every rule.

i think it depends on the situation and the crime and i do think that most people who are guilty of "something" do "pay" for their crime in some way, maybe not what society or certain people demand of the situation but they do pay in other ways.
one example would be: i kill someone who is raping, harming, beating my partner. i am guilty of murder even though i was defending someone. i know that i will "pay" for that in my own mind for the rest of my life although society may not try me or find me not guilty. i am pretty sure i would psychologically have difficulty with the taking of a life even though i could rationalize it away.

I would argue that in the example you gave, morally you would not have committed murder but simply killed in defense. Legally it's called justifiable homicide, a distinction from murder and rightfully so in my opinion. You may be right that you'd feel guilty and have psychological difficulties as a result; some people do. However, such feelings are not necessary if you did in fact act correctly and not everyone punishes themselves that way. Another possible response, for example, is anger at the criminal who put you in the position where your best choice was so extreme and undesirable.

I don't know. In general it's a good rule, although what "pay" means is awfully ambiguous. But I can also imagine that there are crimes where a person might be guilty but shouldn't be punished, perhaps if they hadn't intended to do what they did, or if they were mentally incompetent and didn't even know/understand what they'd done.

i still would have killed someone......... and it would be looked at as a crime until it was determined to be "justifiable homicide". my point was the "paying" for the crime not the argument of what is a crime. our society has determined that it is justifiable homicide but another may not. just as many women who have killed their abusing husbands when they come home and the woman feels threatened and ultimately kills him, are found guilty of murder, for whatever reason............ society may not find it justifiable where you or i might but they are forced to "pay" via jail sentence. i also feel that even the women who don't go to jail probably "pay" in some way because of what they have done.
and you say "morally" i did not commit a murder, i would argue that morally(my individual morals) i did commit a homicide i guess.......... but not legally.

You would have killed someone. It would be a homicide. If the killing was legitimately defensive, it would not be murder. You might well feel badly about it anyway but not all people do. It's easy to say you shouldn't feel bad if it ever happens, but individual responses vary. Hopefully none of us will ever have to find out.

true true

No. Sometimes there is no harm in letting someone get away with something. Especially if it was a one time deal specific to a situation, and something that wouldn't happen again anyway.

You are asking a black and white question and expecting a grey in between answer.
Should, made to...
There are laws and a judiciary team for these kinds of things.

Answering for one's crimes and paying for them are two very different things.

Some crimes, there is no 'payment' to be made, because there was no loss