When you walk trails,looking for bear sign,look very closely.As Sharpster said,tracks can be hard to see,but there will be some.Often,a bare track registers as just a pressed spot in the dirt.It looks like you pressed your palm on the ground.If you pay attention,you will notice that most of the dirt's surface will look rather grainy but where a bear steps,it will have that pressed look,like a man with moccasins made it.Deer can't make sign like that.Sometimes you will find young seedling blades of grass pressed down into it.That's not natural.it tells you something has stepped there very recently.In a day or two,that grass will spring back up.
Bears will often skirt the edge of open areas either just inside the treeline or just outside.Sometimes you can make out tracks in lush green grass.It will look like a man walked through it and you can see foot impressions and can get a rough idea of size.You can even tell direction of travel by which way the grass is bent over.
In the summer,bears roll a lot of rocks and tear apart a lot of stumps and logs.Most rocks you find that have been flipped out,were done by bears.Pay attention to any rotten stumps or logs that would likely hold ants.see if they have been rolled or ripped open.
Look for prominent trees along trails that bears may have rubbed on or marked.The bark may just have a slight rubbed appearance or it may have claw marks,bite marks and bark peeled off.If they rub,they leave hair.Look closely.
On the real marker trees,a boar will stand up and claw and bite as high as he can reach to let others know how bad he is.In this country,most I find are on prominent cedars close to the trail and many lean into the trail.If he has been there recently,you will see the ground disrupted where his feet shifted while rubbing his back.Again,look closely.
Bears love thick stuff and sometimes you find bear trails through low hanging brush that you just know deer are not crawling through.The surface of these trails won't be pock marked by deer tracks but will be smooth like a human foot path.
They have to have water daily and in hot weather,need to actually dunk themselves frequently to cool off.They love all water sources but especially beaver ponds.They like to bed in thick,dark,cool places.swamps can be good for this.
This time of year till a couple weeks before hibernation,they will search out every food source and will try to eat every waking minute.Apple trees are bear magnets in early Fall.They will also be hitting white oak acorns and beech nuts if you have them.
You can make a simple dirt sifter out of 1/4" hardware cloth stapled over a wood frame and sift dirt in patches on your trails.They will leave good tracks in that.If you don't have to travel far,you could even dump sand in them.
Reading sign is like CSI work.If he was there,he will leave sign.It may be very subtle but it will be there.Finding sign like that can be as much fun as any other aspect of hunting.
And lastly,investing in a good trail camera can sort out a lot of stuff for you real fast.You can use bait with them but I prefer to read sign and find good places to put them,just like hunting.