Personal experience. I played W7 with heavy class switching and W6 without (and without reloading at level up), it feels much better.
Traps are too painful to ironman through them (especially if you don't have a thief) and self-jammed doors are also a pain.
I watched TV while rolling. Spent a lot of time, got 18 probably more 20 times in W6 and W7 but never a better roll.

It just means most of my characters are on their way to Hell?

I messed around with the characters a little bit. After-action sounds like fun. Maybe I will start another thread if I am feeling creative.

It rather means you have more Donald Ducks than Gladstone Ganders ;-)

Yeah, "Karma" in this game isn't about good/bad deeds or "alignment"; it's better thought of as how much fate/fortune/destiny tends to smile (or frown) on that individual. A low-karma individual has probably had a rough life, but this can make it easier for some NPCs to relate to them.

Sometimes I try to track the distribution of bonus points because I wonder how the bonus points work. Here is my current guess:

Roll d6 and d100 for 600 possibilities.

Bonus = 20+d6 if d100=11*d6
Bonus = 12+d6 if int(d100/10)=d6
Bonus = 4+d6 otherwise

So the distribution then works out as:

90 each for 5 to 10
9 each for 13 to 18
1 each for 21 to 26

The probability of rolling 18 or better would then be 1 in 40. It is just a guess.

I have another question: Does skullduggery skill matter or can it be skipped? It looks like it is for opening doors, which can be opened with knock-knock, and for identifying traps, which can be done with divine trap. The same question applies to legerdemain.

Legerdemain is is for pickpocketing. This can save you money in shops but you can earn as much money as you want by fighting and pay the stuff you get.

Skullduggery isn't essential for winning the game but it's nice to have.
Near the end I came across an optional door where I cast dozens of knock spells without succeeding (maybe just bad luck) and finally managed to pick it with 70 skullduggery and many reloads.
There's no need to put points into skullduggery at level up but you can have the bard try the doors before casting them open to get a chance for free skill raises if you want. When your bard's thaumaturgy is at 100 putting the remaining skill points into skullduggery won't hurt.

Oh! All this time I thought I had to put 10 points into skullduggery in order to get started! So the bard can start at 0 and pick the locks until they are jammed and gain some points. That makes it easier.

You can in fact start with 0 skill. With luck or reloads (locks difficulty is randomly chosen at your first opening attempt) you can even pick the first door starting with 0 skill with the skill you gain at the first failed attempts there before.

Jammed doors are a pain however so I'd just save, have the bard try to pick 2 times or so and cast knock-knock immediately afterwards until success (if it doesn't work the door got jammed and I'd reload from before the first attempt).
Putting some extra points into skullduggery makes things more comfortable.