In some instances, no doubt true. However, we had an aircraft u/s from April until about October (that one was actually due to a student having a bad day - namely me!) That was not due to the fact that the club do not care for their aircraft, it was simply down to the Germans not getting on with providing us with the spare parts! So u/s stickers are not a true indication of the club's treatment of the aircraft...
A whole aircraft u/s in a bit different to a piece of equpiment inside being u/s, unfortunately my experience is that the school hasnt fixed it for their own reasons. Dont forget its all about perception as well, especially if you are trying to attract new students/hirers.
A single u/s sticker, yes ok but when multi ones appear that is what creates a bad impression, whatever the underlying reasons are. Unfortunately the kit was u/s at the school I used I needed for what I wanted to do so that led to me buying.