Could be scent. Stand placement. Not entering your hunting grounds INTO the wind.
As Dr. Ken Nordberg once said "Where there are does there will be bucks."
They're just more 'leery.'
When I started paying attention to more of the DETAILS I started seeing (and taking) more decent bucks. Details were:
1) Scent control. I shower in the AM before every hunt with Hunter's Specialty green soap. ALL hunting clothes are washed in the same soap and left on the porch all night to air out. Boots too. I never get gas or go to a gas station the day I am hunting. I don't smoke, eat strong foods like onions, or garlic. I dress light for my walk into my stand and then put the 'heavy' stuff on when I arrive at the stand.
2) Noise control. I don't cough, clank metal objects, etc. while on stand. I pretend that there MAY always BE a buck within sight or scent distance even tho I may not SEE them myself yet. I sit quietly and turn my head in slow motion. I remain quiet, still as much as possible. I don't pee on the ground while on stand. I keep a plastic bottle in my pack to urinate in and seal and take out with me from the stand.
3) Homework. Before the season I want to scout the land and see what FOODS there are, BEDDING areas, TRAVEL lanes, STAGING areas, etc. remember - EVERYTHING a buck does during hunting season is governed by his desire to breed, eat, and sleep. he will do everything to avoid being detected and if over the age of 2 he knows just about what he needs to know to survive another season. While they tend to get more careless this time of the year they aren't stupid either. THINK like them and your odds will improve greatly. Bucks prefer not to travel out in openings unless its pitch black out. I position my stand in the STAGING areas or FUNNELS. A buck will linger from about 1 hr before sunset in this STAGING area and will not enter an open field unless MOTIVATED highly or unless he feels REALLY safe. Catch him on one of his runs on his way to the FEEDING area or where the does have been hanging.
4) Use good camo. Don't silhouette yourself in the tree line against an open sky. Don't over trim shooting lanes, etc. Bucks know when people has messed with their runs and security of foliage.
5) Remain POSITIVE in your choice of stands. BELIEVE that you WILL be successful and ARE doing everything RIGHT and that its just a WAITING GAME. Remember, the MORE you hunt and are out there the better your ODDS get!
I am always amazed at the number of hunters who invest large amounts of money in their super hot bows and gear only to go out and sit for 1-2 hrs and get 'itchy' or 'bored' only to get up and start moving around or they leave too early. Patience is what makes the good bowhunters great! We WAIT it out. We hunt hard, smart - right to the very end.
Hope this helps.