If/how the different levels of poison affect ability to apply it?

The guides say normal poison to 60-70 skill and then greater and also people say that 80 poisoning is enough because you never poison yourself on acccident after that.

Does taht mean that you still have a good chance to apply Deadly at 80 skill?

Good question, I'll have to check when I get home but I'm somewhere's around 88 Poisoning and have a pretty decent success rate (probably 80-90%) but the thing is, I forget if I'm using Greater or Deadly. (I'll check on that later and update)

I've probably poisoned myself maybe once in the last 20-30 or so times I've poisoned something.

I only poison 1 item a day once, for what it's worth.

Ive been doing the blackrock training on it and I give supreme credit to anyone who has trained this skill past 40 without aid of the motherlode. Im going insane even with the infused gains...

I think Im going to take it to GM if I can anyway, but I was just wondering so I can include taht when I do the FAQ for it...

I trained it to 80, sitting in my house, and poisoned myself ALOT. Bad thing was I stripped the char of all skills but chiv and poisoning.... I was red, had no karma, and failed alot. So i used ALOT of cure pots.

I only have 80 poisoning, and have been using it for over 2 years now. I don't know when it stopped, but I can tell you that I've never poisoned myself. Of course I only use it to poison some more shurikens or re-poison my dagger or kryss, and only end up using it maybe once or twice a week.