What are common mistakes you've seen when teaching new players?

Yup. many a time I've taught newbies they've had problems differentiating stealth from Action Modifiers and Action cards that have built in stealth.

TwoRazorReign's suggestion sounded pretty good at a glance:

"Abbott (current text):
+1 stealth action. Requires a Sabbat vampire.
Put this card on the acting Sabbat vampire and untap him or her...

Abbott (revised text):
Requires a Sabbat vampire.
Put this card on the acting Sabbat vampire and untap him or her (+1 stealth)..."

self wrote:

I don't think that's much clearer (if not less clear) than the way Stealth is already described. that's just me though.

So, the idea isn't necessarily to make the description of how stealth works clearer via card text. That ship has sailed long ago. It's more to remove the persistent confusion among new players who try to play action cards for stealth. With that said, you bring up a good point, and making things less clear in the process of fixing something else should definitely be avoided. In that sense, there certainly would need to be an explanation in the rulebook what the parenthetical stealth modifier on action cards means. I'd imagine it would go under 6.1.6, where it explains that unless otherwise noted, action cards are played at 0 stealth.

Ankha wrote:

the card is an action (action symbol). Actions are taken by default at 0 stealth. All bonuses (+bleed, +strength, +votes) are expressed as "+" modifiers.

I'm opened to suggestions.

It does not have to be that way. Actions could define the relevant base amounts in absolute terms, and modifiers be written with +. So for example, Dominate Kine would go from:

+1 stealth action. Bleed with +1 bleed.

to

1 stealth action Bleed with 2 bleed.

Bonuses on action card are a vestige from Jyhad where the values on vampires were considered base values (e.g. 2Strength instead of +1 Strength), but that was changed long ago.

Finally, it would save card text to change the default in the rules to 0 Stealth for actions and 1 stealth for undirected. I guess this alone would remove more than half of the stealth mentions on action cards.

Non-existant user wrote:

Ankha wrote:

the card is an action (action symbol). Actions are taken by default at 0 stealth. All bonuses (+bleed, +strength, +votes) are expressed as "+" modifiers.

I'm opened to suggestions.

It does not have to be that way. Actions could define the relevant base amounts in absolute terms, and modifiers be written with +. So for example, Dominate Kine would go from:

+1 stealth action. Bleed with +1 bleed.

to

1 stealth action Bleed with 2 bleed.

Bonuses on action card are a vestige from Jyhad where the values on vampires were considered base values (e.g. 2Strength instead of +1 Strength), but that was changed long ago.

Finally, it would save card text to change the default in the rules to 0 Stealth for actions and 1 stealth for undirected. I guess this alone would remove more than half of the stealth mentions on action cards.

It's a good suggestion, but I don't think that goes far enough to fix the problem. The stealth modifier should not be the first thing mentioned on action cards. New players see "stealth" at the top of the text box and want to use it. I'd actually argue that the stealth modifier should go last wherever possible on action cards. Action cards, which are often complex and can contain a lot of text, should have a "inverted pyramid" structure to the text: the most important information should appear first, followed by less important information. In other words, requirements first, a description of what the card does next, and stealth modifier last.

TwoRazorReign wrote:

[So for example, Dominate Kine would go from:

+1 stealth action. Bleed with +1 bleed.

to

1 stealth action Bleed with 2 bleed.

This might also not be the clearest wording as some people might think that the "1 stealth action" would mean that you can't increase the stealth.