Redpost Golf-Training Aids Help or hindrance?

Are golf training aids useful or are they just another way of conning people to pay more money for the sport they love?
The only training aids I have ever had were ones that were given to me one was  a gadget that you pushed into the grass and had a ball suspended on about 6 inches of string from an arm above. The other one was a Velcro driven thing whereby you had to fix a tee into the end of your club and if I remember rightly strap it onto your wrist and onto the tee in some way. The first one ended up with the ball becoming detached from the string and disappearing into the distance and as I was not inclined to drill another hole into another ball this aid was quickly despatched to the bin. The Velcro gadget was so time consuming to put on and did not seem to improve anything about my golf swing. So like the first item it was sent to the same place.I have seen and I am sure you all must have seen the plethora of other training aids from hinging golf clubs with Henry Moore sculpted grips to two meter diameter plastic rings on a specially and scientifically calibrated stand. There are also aids which comprise bungee cords which can be attached to the nearest tree to make sure your rotation is correct, putting aids which anyone with a little bit of draughting and DIY skill could knock up from a piece of hardboard and a bathroom mirror.
I have found the best way to train for golf is to look at some professionals tips such as swinging a putter through a line of tee pegs or practicing the basic principles on a regular basis. When I was first introduced to golf having been given a course of lessons, the first lesson was just about grip and I was told to go away and practice this until the next lesson. The lessons taught me all about the acronym GASP-Grip, Alignment, Stance and Posture and when I find myself doing something wrong which as I get older happens more frequently I revert back to these basics and 9 times out of 10 they seem to work. I don’t believe being anchored to the ground or using any other mechanical device is going to help me.
I will happily concede there is one mechanical item that has helped my golf, but it is not to improve my ball hitting , it is an electric trolley to preserve my back so I can go on playing into old age
As you can gather I am a Golf Training Aid Sceptic so I would be interested to hear your comments on whether you think that they might be useful.
Please try and convince me.