Is my horse supposed to chew on the bit?

[Rivonia]

This often happens to me with various riding school horses, and my instructors always said that it's a good sign. However, I found quite a few articles which say that it is not desirable and that it is means that the horse is not comfortable (either with the bit or with my hands). So, which is it, good or bad?

 

[Shay]

Horses should be able to mouth the bit and ideally produce some foamy spit. But they also should look relaxed about it. A horse that looks frantic or is tight in the neck, sometimes if it is producing loads of spit, or none at all, could be signalling that it is uncomfortable. Its a bigger picture than just mouthing. Sorry - very little about horses is simple!

 

[Exploding Chestnuts]

Ideally the mouth should be moist, but the horse should not be chewing the bit as such, a few do, but certainly not many.
If the rider's hands are not sympathetic, ie capable of light contact in rhythm with the stride, and are therefore independent of your seat then the horse may object to getting "jabbed", this is why it is important to develop a good position, so that you can maintain contact though the reins without annoying [and unbalancing the horse]. Concentrate on a nice position, sit up straight, plenty of practice, and your riding will improve steadily.
If you hold a horse too tight or collect him for too long he will stiffen up, so it is important to walk on a long rein between exercises to allow him to relax.