In reply to TainaJ:
> we found out that guidebooks are not that good ... Meant more for people who already know the area anyway.
Can't say for certain without knowing the books you used - but most walking guidebooks for Scotland are intended to be used in conjunction with a map and compass. You use the guidebook before you set off to work out the route on the map, and then use that to actually find your way. Most people then leave the book in the car.
> Sometimes difficult to find where the track starts, so having a sign at the start would save time
That can be a problem, yes. Some tracks
are marked where they leave the road - by eg Scottish Rights of Way Society, or National Trust, or local estates where they want to steer people onto certain routes.
But you can start just about anywhere, sometimes following a path, sometimes not. It's not practical (or desirable) to mark every one.
> We thought it odd that some people feel the need to destroy cairns made by others to help people find the way in places of difficult navigation in a fog. We thought that the real and true reason behind this is that they want to keep the mountains to themselves
The main problem is that such cairns proliferate, and you end up with a line of huge piles of stones often several metres across - an eyesore (there are countless examples of this in Snowdonia or the Lake District). And also, they're often constructed in inappropriate places, where they can hinder navigation rather than aiding it.
Occasionally they can be useful - for instance, marking passes on the Cuillin Ridge, some of which are so seldom used that there is no path to tell you the safest point to begin descending. But if there's a line of cairns along the ridge, then you can no longer know which one marked the bealach.