OTS is a curse or disease that allows the sufferer to endlessly ponder, reflect, worry and hold an inner dialogue/self-debate about all things in life!
English slang which can mean feeling poorly or can describe something as useless or unfit for purpose. So if someone says they feel like shit warmed it means they are feeling extremely unwell or under the weather. But if it is their opinion of a device, person or product, it means that the device, person or product is a total WOFS.