Biscuit was all over the place because he was allowed to do so by whom ever former owner threw up there to ride him (read anyone and everyone - most people had never rode horses). So when I got Biscuit I have found that to not make a pleasant ride for me. The barn manager has helped me and he is actually being ridden by a trainer 2 times a week to learn his aids better and to specifically train him to go straighter. Barn Manager does alot of dressage training and said going straight is a very hard skill for horses to learn. Biscuit tends to arch his entire body and double track with his front and back hooves...even if he is just cantering free in pasture and arena.
I ride sometimes with a very nice lady who lets her horse be all over the place.
She cuts in front of you, weaves in and out, pushes people over, etc. Her mare (both of them actually) do this because she allows them to. It makes for a very nerve wracking ride because the old mare will kick and the young one will snake her head at Biscuit, ears flat teeth bared. Now she never actually bites and now won't do it after I got onto her while doing her feet (she was actually well trained until this lady got her!). But there have been a few times that it made for an unfun ride for me.
I rode with her a week and a half ago for 4.5 nerve wrecking miles. My cousin and I and our horses were a nervous wreck
when we dismounted because of her weaving in and out, speeding up, slowing down...she was all over the place.
So yeah, I think it is a big deal for other people you are riding with. I have had to work every single ride with Biscuit to get him to GO straight. If you are on the trail by yourself or with one other person and they are ahead of you the drunken sailor mode won't effect them.
Biscuit has improved so much by not allowing him to just drunken sailor along - teaching him his aides, etc. Makes for a much more fun ride for me!