Both my son and I have dived with many different operators on GC, most recently two weeks ago with Jason at Ambassador divers. Our experience with Jason was quite positive and we found all of his gear to be in good shape. No one experienced any equipment malfunctions on the days we were diving with him and no one complained about any of the rental equipment either openly or "just between divers". We also used rental equipment up at turtle farm and at Sunset House on this trip and did not have any issues or problems with their gear either.
I would have to repeat that we have had similar experiences with various other dive operators in GC on other past trips. Maybe we were just lucky to have somehow missed a bad experience, maybe not. Frankly I am known to have a bit of a critical eye, so minor details do not tend to escape me easily.
Like any business I think we all have to understand and appreciate that dive operators are not going to be buying $800 BC's to rent for $10 a day. Similarly we also have to recognize that they are going to try to get as much useful life out of their equipment as possible before replacing it. Most dive operators are small businesses and they depend upon repeat business and referrals. People who have a good experience tend to tell few people, those who have a bad experience tend to tell everyone. A smart business operator doesn't want anyone bad mouthing him/her and he/she certainly doesn't need or want the liability that would come his/her way if a piece of equipment did fail and someone was injured or worse. Like what was previously posted... if someone doesn't like the quality of rental gear or is worried about the maintenance history it becomes a perfect time for them to step up and take responsibility for owning and maintaining their own gear.
Anyone making negative accusations simply based upon the aesthetics and without considering what the constant use, sun, and salt water exposure does to the appearance of equipment isn't being very realistic, in my opinion. How a piece of equipment functions is what is really, really important to me and hopefully to anyone who is a serious diver.
In all fairness to the dive operators on GC I think anyone who has had a negative experience with gear should quantify what was wrong and why. Broad generalizations do not help and only serve to unfairly spread rumors. Anyone who has actually experienced an equipment related issue with rental gear should report what happened candidly, honestly, and objectively. Let's also not forget that when we are discussion equipment issues there can be all sorts of causes... design defects, manufacturing defects, shipping damage, normal wear and tear, environmental damage, user error, storage, cleaning, maintenance, etc., etc. And in all fairness to the dive operator not all of these potential issues are within their ability to control or prevent.