Many business cards have complex graphics or textured images behind the text which can throw off an OCR scan almost entirely. Business cards with a lot of "visual clutter" causes OCR (on any scanning application!) unable to discern between image and text.
Textured business cards require more careful picture-taking when trying to get a good scan out of the image. For instance, strong lighting from any angle can create small, but distinct, shadows on the card, worsening the scanned results.
Cards with very busy backgrounds, or a strong amount of "visual noise" might be unable to scan well at all. Try cropping out textures and images from the card image, down to just the necessary text, to get the best results.