I have heard, a little bit of tannin helps hide the scars, im not talking about roasted turkey tan, just a little colour :)

I would think it would take away the red on top of pale skin (do you have pale skin?).  The tan background gives a different background...more subtle scars/acne.  Another scar hider...freckles.  Though you can't get those on purpose.  lol

I have heard two sides - one, that the sun is good for curing your acne, and another, that the sun is actually harmful to your acne. I really am not sure which side is correct, but is anybody else confused by this?

I would say this. The sun is so bad for scarring. If you have scars you should be wearing sunblock, well you should be wearing sunblock anyway. Sure getting a tan has always been better for my skin and getting rid of some acne, but I'm a lot more carfeul now when in the sun. When we are young we feel that we are invincible, now that Im a bit older I realize I need to have sunblock on all the time. I still get a tan, I just don't become a red lobster and cause further damage to my skin!

I have always found that the sun dried out my acne some. My guess is that the UV light helps to kill the bacteria that makes them thrive, but I'll be honest in that I don't wear real sunblock. I have a moisturiser that has a low level block in, but anything else makes my zits worse.

Agreed, and from my point of view too much is a killer because it sets off my rosacea and leaves me itchy, hot and looking like I have a sunburn even when I had total sunblock on. It's just a temperature thing for me, like with the shower being too hot and causing it.

I guess that makes sense, I mean, I can see that a sunburn can probably make your acne worse, but in moderation, I'm sure that it can help out a lot if you take the proper precautions.