It really depends. The "better" companies have their own art department. Art departments consist of a staff that work full-time with images. They process images and create graphic designs for a living. When sending images to these companies, you really need to send the entire image. These people will know a cropped image instantly, and sending a cropped image makes yo look like a real amateur. Trust me, I have learned this the hard way.
If you are sending to a company that does not have full time, professional graphics staff, then chances are they will never know you are sending a cropped version of the image.
Another thing to remember is not to sharpen any images you submit. This is another thing that raises the red "AMATEUR" flag immediately. No professional designers or art directors want to receive an image that has already been sharpened - they like to do this themselves, according to their preferences and output size.
"Your" and "you're" are different words with completely different meanings - please use the correct one.
"They're", "their", and "there" are different words with completely different meanings - please use the correct one.
"Fare" and "fair" are different words with completely different meanings - please use the correct one. The proper expression is "moot point", NOT "mute point".