Wind.. always the darn wind! I'm all for "Scent-Lok" this and "Scent-Blocker" this, but I personally feel unless you are a millionare and buy EVERYTHING scent free and everyone that hunts with you does too, they only "help", barely. I absolutely hate these ads that say "Forget the Wind... just Hunt". Well, hunting is all you do.. shooting and killing you won't! I take the Real Estate approach... the 3 more important things.. Wind.. Wind.. Wind.
Tactics we have picked up over the years (about 10 hunters in the family/"gang" - 100's of dead Elk - some 350+ class bulls - rifle and bow):
1) Don't over Bugle and learn to listen the Elk. You can tell when a Bull just wants you to answer him so he knows what direction to push his Cows.. AWAY FROM YOU! Learn to chase those. Become a "lost cow" trying to catch up to the herd or join him. You might be surprised when he holds a bit or comes back to get you for his herd. (This really works earlier in the year when they are herding cows)
2) Don't become the Bugle champion of the world. Have you ever really listened to a bull elk in the wild? He's a growling, gargling, sometimes horrible sounding beast. The "best bugle" sometimes sounds so good it drives somewhat decent bulls away thinking you are a herd bull and nothing will mess with you! Also, some big bulls get used to the perfect bugle equals man or the old..... eh.. I'll just hold up at 100 yards and you come to me bull!
2a) Change up your bugle and sounds. Play with em! I don't think you can produce that bad of a bugle to scare them off. Unless you start squeeling like a dead rabbit!
3) WATCH and just don't stare at one bull... anyone who has chased Elk alot knows of the infamous "Satellite Bull". Some bugle leery bulls without cows will come in silent trying to steal a cow or two. This is very common with rag bulls or even spikes. Big, roaming bulls will do it too.
4) Become a herd of Elk. Walking around won't spook Elk (before you've actually spotted them or close, etc.), especially if you and your hunting partners mix in calling and talking like a bunch of Elk. We really like the Calf/Cow combo of sounding like a herd of Cows and Calves. They seem to like company and will bunch up in bigger herds. Bulls know this.. they will come. More COWS equals...
With all of this said, we like cow calling alot more than bugling. We usually bugle to find them and go from there. Every now and then you can really bring a bull in close bugling back and forth, etc. In my opinion, this is "Hollywood" hunting and usually works in the movies or dead heat of the rut. Overall, good cow calling and herd bull chasing can't be beat.
Anyway, hope this all helps and good luck hunting!!