I'm with dogdollar, a lot of these roosters seem to behave quite normally - from the rooster's perspective - and getting killed because we humans misunderstand their perspective. Certainly there are some that are just plain mean and aggressive and can't be safely kept, but most of these stories don't sound like that kind of roo.
From a rooster's perspective, there are basically four kinds of animate objects:
1) Hens
2) Other roosters
3) Threats to the hens
4) Everything else
Hens of course are to be protected from (2) and (3). Other roosters must be challenged and fought until they accept their place. Threats to hens must be faced down, attacked, and driven off. Everything else can be ignored.
So, if you act like a rooster, you get challenged and possibly attacked. You can fight back, confirming that you are indeed a rooster; if you win, he may accept his status as second-fiddle, and things go well. Or, he may wait for another chance to try you again - if he's a strong, dominant type, he may never accept the secondary role, and you'll get challenged repeatedly, unless you change YOUR behavior and convince him you aren't a rooster after all. This shouldn't be that hard.
If you act like a threat to the hens, again, a strong roo will attack you to defend his flock. There must be ways to check hens for health without making it look like an attack. Also this is probably related to flock size and confinement; expect more aggression if you have less than 10 hens per roo, or if they are confined in a small area.
Not everyone here agrees with this approach, but I find Robert Plamondon's analysis convincing:
http://www.plamondon.com/faq_roosters.html