I'm not sure what the secret is. Maybe you'd care to share. See, I've "gained" -4372 credits over 8 hours of slicing...
This is with 3 companions out most of the time, 4 out sometimes, 400 level slicing, doing Rich level 41-49, The Automated Saboteur and Be Careful What You Read whenever available. As of 3 hours into this 8 hour period, The Automated Saboteur disappeared and I haven't seen it since. During this time I also got 3 purple missions and 7 blue missions. That is all.
So yes. In 8 hours of grinding Slicing, I have lost over 4k credits. This is not to mention all the crew skill time that was wasted.
Please, tell your story of slicing misery here.