Why do some cheek implants look like balls in the faces of the patients?

Cheek implants offer a permanent augmentation to the mid- face area when there is loss of volume. The size and the shape of the implant is very important, which is usually determined  at the time of the consultation and examination. Experience of the surgeon also matters. It is best to under-do the implants, not overdo them which can give a unnatural appearance. For more information, diagrams of the implants, and many examples, please see the video and the link below

It is difficult to say whether a person has had Plastic Surgery from a photo and also to determine what kind if they have had it.  Cheek fillers, fat injections and implants are all used to make a cheek appear more full.  Any one of these treatments can contribute to a 'overly' done look.  I find fat transfers to be the most natural appearing since they are your own tissue and can be added in stages to the effect you want.  

Hello and thank you for your question. There are many options to enhance and rejuvenate the cheeks in a natural appearing manner.  If malar implants, fillers, or a SMAS facelift is performed with good technique, this can achieve a natural look.  Make sure you specifically look
at before and after pictures of real patients who have had this surgery
performed by your surgeon and evaluate their results.   The most important aspect is to find a
surgeon you are comfortable with. I recommend that you seek consultation with a
qualified board-certified plastic surgeon who can evaluate you in person.
Best wishes and good luck.
Richard G. Reish, M.D.
Harvard-trained plastic surgeon