They decide a particular scripture does not apply today when it doesn't conform what they believe is "fair" in today's society. They trust in Scripture only when it suits their purposes and when it doesn't, they twist it so that it will.
That is absolutely, 100%, false. I don't know a one evangelical who does this.
The issue is not with the authority of Scripture. The Word stands and applies to us today. This issue, though, is that we can't make it say something to us that it didn't originally say. Paul was speaking to a people who lived in an extremely restrictive culture in respect to gender. That does not necessitate that the culture remain that way, nor does it apply universally. The passage is still inspired and useful for us today, but it is not a blanket, overarching statement.
Should we own slaves, as is mentioned other places? There was a time when people used this very same argument about owning slaves, but I don't know any who would hold that we should follow the same logic with slaves today. What about women praying with their heads uncovered?
The Bible doesn't change. The meaning doesn't change. But the audience does. Women, of course, wouldn't be allowed leadership at that time.
Additionally, there are many times when God, in His sovereignty, allows injustices to go on for the sake of the Kingdom. Polygamy anyone?
Also, we see a trajectory throughout the Bible of women gaining more and more freedom in culture. The same cannot be said of homosexuality or something like that.
For further reading, I would suggest the writings of N.T. Wright,
Slaves, Women, and Homosexuals (can't recall the author right now),
Beyond Gender Roles by Gilbert Bilazikian (sp?), and
Finally Feminist by John Stackhouse. Also, Gordon Fee is very helpful