I find it hilarious that everyone is confused. Guilt? Conscience? Anyway, I've seen some ridiculous things here. It's obvious that the average person engaging in black hat has more flexible ethical standards the the average person. However, the average person is a complete moron. Ethics are complicated.
There are so many variables involved that it's difficult to judge right away whether something is unethical. Take a site marketing a Clickbank product that is completely worthless. Yeah, the person is stupid for buying it, but it's not nice to exploit people. Nonetheless, there are useful products to market that will probably sell better anyway. I don't market products (I might try sometime), but it's not due to ethical objections.
I'm studying philosophy, and I can probably argue that just about any career is unethical. There are just so many factors to consider. I wonder what you're doing that makes you feel bad about it?
As for your conscience, it's significantly the result of natural human empathy and socialization. If I lie for a good reason, I usually feel guilty. I shouldn't feel guilty, and I feel less guilty than I used to feel. It takes times.
In philosophy, there is a debate over whether or not you should push a fat guy into a train if it will save more lives. I thought "no!" but my mind say "yes." My conscience was very opposed to pushing people into trains. I thought about it long enough, and I am now emotionally critical of someone who wouldn't push the guy. You can actively shape your conscience by logically telling yourself why you should or shouldn't feel X.
If you want a quick fix to feeling guilty, donate a significant percentage of your income to a worthy charity. Oxfam is good, apparently, though I don't know if I agree with prioritizing aid to starving people (for complicated reasons). Just pick something that you would feel good about.
The reality is that the average person is a selfish "insert expletive" that deserves to be stolen from and beaten with a bat - myself included. The fact that people in our own neighborhoods, sometimes family, are suffering from things we could easily eliminate is really ridiculous.
Basically, you don't have to do much to even it out. Just Robin Hood it up and redistribute some money to something useful. You know keeping some is alright because you wouldn't keep earning and donating if you didn't (cause you're a bad person like everyone else, most likely).
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Personally, I haven't done much that isn't white hat. I created another account on a website using a proxy and spammed some links using a program once. You can rationalize almost anything so I wonder what you've been doing now.