Clothing doesn't always fit correctly, but I can almost always make it fit. Magnets, the Tailor, turning body parts invisible, postwork, whatever. If it still doesn't look good, I'm more likely to try different clothes than to change the pose to accomodate the clothing. IME, changing the pose to fit the clothing often results in that stiff "mannequin" look that tends to be the biggest flaw in Poser images.