If a creature needs to be subjugated you'll get a message of "you must subdue this creature before you can tame it" rather than an anger message. Swampies don't need to be subjugated though. Basically, there are two anger messages you'll get with pets during taming - "you seem to anger the beast" and "the creature is too angry to continue taming".
Angering creatures is just a normal part of taming certain aggressive creatures. If you try to tame you'll either start a tame attempt normally or you annoy it and "you seem to anger the beast" flashes up. The higher your taming skill, the less you'll see the anger message, but it won't ever go completely. The best solution is a tame last target type macro which either has a number of repeats in it (Enhanced client) or you can simply hold down a key which is tied to a macro like "use skill animal taming, last target"
If you're getting a message during the tame which says the creature is too angry to continue taming, that means basically you got too close and you've hit the animal. If you keep a tile clear between you and the dragon at all times you won't have trouble with it. Carrying either a very slow swing speed weapon or a bow without arrows can also help - if you accidentally get too close, you shouldn't score a direct slap on the dragon's nose before you back off again.
Hope that helps
Wenchy
