Why wouldn't you? Adam was more 'perfect' than the entirely sanctified, yet he succumbed to temptation.
The mere fact that one can move in and out of entire sanctification is in itself contradictory. If I reach a state of perfection I can ward off any external temptations perfectly. It would be impossible for me to fall for any external temptation because of the "nirvana" of internal perfection, a state of being that has reached a state of perfection and once that state is reached the possibility of falling out of the state is impossible because how can perfection be tainted since it necessitates the ability to perfectly subscribe to all moral good at all times regardless of temptation and thus a state that once reached is incapable of anything less than perfection.
This is why we modify the term 'perfection' with the word 'Christian,' and often use the term entire sanctification instead. Perfection does not necessarily mean faultlessness or impeccability. It can also mean complete or full-grown or mature. It is this definition that fits most closely the Greek words that we translate as 'perfect' (telos). In the Christian sense, it is simply loving God and man with one's whole heart. This doesn't rule out temptation, nor does it rule out sin should one let other concerns creep in. Nor does it rule out spiritual growth. In fact, it allows for unimpeded growth, since one is no longer fighting oneself to do God's will.
The real life problem with such piety is that we are so concentrated on the inner man we forget to live within the world and create the Kingdom of God which is our task. This Kingdom is not merely a spiritual Kingdom but one that extends to all areas of our life. We live in the temporal world and God calls us to take dominion over it. If our concentration is focused soley on the inner man we disobey God's command to take dominion over his creation.
This does not follow from the doctrine of entire sanctification: in fact, entire sanctification is seen as a focus entirely upon God. The focus on God means that we do not concern outselves with the 'inner man' but live in the temporal world, seeking to create the Kingdom of God on earth. A contemporary of Wesley, an Anglican vicar who was Wesley's heir-apparent as leader of the Methodist movement until he died, John Fletcher of Madeley, claimed to be entirely sanctified, and his life showed it--he took over the parish for the town of Madeley, a town full of sinful characters that would not be bothered to go to church. He turned the place around. The infamous atheist Voltaire once was asked by a fellow skeptic whether he had once met anyone who was like Jesus Christ; his reply? "I once met Fletcher of Madeley."
Finally, the doctrine of entire sanctification diminishes faith and leads to spiritual pride. The fact that our flesh is weak and full of sin should lead to a humility and deeper faith that relies upon God's power and not our own. If we falsely believe that we have reached a state of sinless perfection then we no longer need to rely on God but can seem satisfied in our own accomplishment. This sort of attitude strikes against the entire gospel that calls us to rely soley on Christ and not our own deeds and to exalt in our weakness because it exalts Christ.
This is precisely wrong. The doctrine of entire sanctification requires that our faith in God be great, because God is the one who grants and maintains that state in us--without him, we cease to be perfectly loving, as he commanded (Mt. 5:43-8). This is similar to saying that the doctrine of salvation by grace through faith alone strikes at the heart of the gospel because many people in the past have come to see their justification before God as an excuse to sin. "What shall we say then? Shall we sin more, that grace may abound? God forbid!"
ps If perfect spelling and grammar are required for entire sanctification I shall never reach that state. ;)
Don't worry, it's not. I just had to say something, since I'm "The Grammarian."