Well, I am a dragon hater, and in reply to the first few post I will tell you outrigt that killing Saladrex is wrong. He is there guarding a hoard of his possessions, much like Humans and banks. Saladrex does register as evil, and he is evil, and unless you have the alignment fix, don't EVER go by game alignments, because your major Domo, and your Play supervisor, and High priestess Demin are all evil, and that Otyugh in Irenicus' Dungeon is NG.
Now, there is a clear line between evil and threat. Now good believes in either self defense, or preemptive strike against a threat. Killing something because it is evil is prejudice. Though one can assume that Saladrex might do evil stuff if he gets out, he is no immediate threat to you, unless he attacks, and no dragons in BG2, except the one in Suldanesselar, attack first.
SInce Saladrex does all he can to keep from fighting you, whether this be good intention, fear, or lack of concern for human affairs, the point is that YOU provoke the fight, so it is reasonable that YOU be held responsible.
Now, if you want to kill Saladrex, I approve, but it is not the GOOD thing to do, nor even the MORAL thing. Generally, you either kill him for his loot, which is theft (Murder 1 in Human terms, Armed Robbery and Homicide), or because he's a dragon, which is prejudice (A Hate Crime). The notes in parentheses are to illustrate why you lose the VIrtue, and what the equivalent is in modern Earth.
Another thing is the Shadow Dragon. This guy is also evil and he killed Mazzy's party (though I am sure Saladrex's hands are not clean either). But he serves a greater evil. If you notice, all but the most evil of dragons just leave people alone in exchange for privacy and gems. Some dragons eat gems. (I am feeling my hatred wearing off and I see some dragons just kill for food, like Lions. Tears form
). Now, if he works for an active evil, but is a passive evil, there is no real reason to kill him. Killing him is more justified than Saladrex because this guy actually CAN hurt people from his location, but he has no interest in doing that. I know, at my office, a very nice young lady who works as the slave-assistant of my evil manager (Not really slave-assistant, but she does all but floss the harpy's teeth). I don't run off punching her in the face because she serves evil (Though she also serves my good manager. What a nice lady that one is
)
Anywho, my reason for killing Dragons and Drow and Mariliths is prejudice. This prejudice stems from their arrogance clashing with my own. Dragons just think they are better than everyone else, and Drow are worse with their female supremascist views (It is my business to dine on the brains of amazon-idiots who think men do not deserve to live.)
BUt the point of this long discussion is that killig Saladrex is an evil act. This message brought to you by a hardcore Dragon-Hater. BioWare will confirm this.