They assert it simply painted a happy face over the party's hard-line conservative positions. That's a little unfair. The convention gave respect and attention to abortion-rights Republicans, minorities, supporters of affirmative action, and even a gay speaker. The party showed a willingness to listen, if not to change. That's not exactly a sham.
Republican strategists are certainly aware of the danger.
Republicans expect Al Gore and the Democrats to make the same attack on them this year. Play to the deep mood of politics fatigue in the electorate. Bush set up the argument in his acceptance speech. I do not need to take your pulse before I know my own mind. I do not reinvent myself at every turn.