I guess defective is too strong a word because it does inflate and keeps me afloat 90% of the time but the issue is that, because it's a very old BCD, the cummerbund velcro closure does not engage very well anymore and tends to "rip" apart when there's pressure applied from my torso area. There's also no adjustable snap closure in front of the cummerbund to keep it secure. I wonder how it would be perceived if I jumped in there with a harness/wing setup?
Although the experience is in the past, it is an issue that comes up more frequently than it should, and student divers are not always aware of how vigorous they can and should be in attempting to correct it. A shop or instructor offering diving instruction, where provision of equipment is part of the contracted price of the course, has a reasonable obligation to provide safe, functional equipment, independent of any other business motive such as impressing stduents and motivating them to purchase their gear from the shop. It is nonetheless common practice for many shops to use older, more extensively used, equipment for confined water training - pool work. The situation you experienced as far as the gear condition for your confined water work is not altogether unheard of. The often high chlorine content is hard on the gear, student lack of familiarity may lead to some level of unintentional abuse, and shops conducting a high volume of training put a great deal of wear and tear on equipment. Frequently, shops will rotate rental gear from their rental inventory to their pool inventory, when the gear is no longer apporpriate for rental, but still functional. I train students through a shop that maintains an extensive rental inventiory, an equally extensive stock of gear used only for open water checkouts, and a third inventory of gear for pool work. New gear is put into the rental inventory as needed, and rental gear is moved to check-out stock as appropriate. Check-out stock may be moved to pool work, and gear no longer sutitable or repairable for pool work is retired. We keep approximately 20 BCDs at the pool for classes, with a variety of sizes. At times, we may have an entire class (8 students) using M/L BCDs and there aren't enough in the pool stock to go around on a given evening. Usually, we will attempt to use an adjacent size, rather than taking one of the BCDs from our OW check-out stock, but will do that if necessary. I am not sure I agree with Jim's early comment that the absence if a quick release waist buckle was a MAJOR defect for a pool BCD. But that absence, coupled with a poor fitting BCD with worn velcro is not ideal by any means. As for a student diver showing up with a BP/W for pool work in the middle of confined water training, it would probably raise some eyebrows. The same with showing up with gear purchased elsewhere. Nothing wrong with that in concept, though. With a BP/W rig, when all other students are in jackets, an instructor may ask that it not be used, as the rest of the class, and the instructor, will be in a jacket BCD. That should be a matter of discussion, not confrontation from the instructor.
Any student in the situation you described during training has a very legitimate basis to speak directly to the shop owner, if the instructor is unable to address the equipment issue, and request that a fully functional BCD be made available- you were paying for it as part of the course. The good news - you got through the course and the experience. Hopefully other student divers will benefit from the comments in the thread.