Customers saying "this has changed recently" means little. For example, I found such reviews for a pet flea product. When I investigated further I found similar reviews both very recent and going back 4, 6 and up to 8 years. Perhaps there are random bad batches but I suspect that part of the problem is the perception that a product is different. People often fail to recognize other factors such as changes in their own usage patterns, or in this case, changes in their local flea population.