To begin with I think this a GREAT topic! I see alot of guys go out and buy some new fangled product guaranteed to bring in the "big" buck only to just be parted with their money with limited success. Whether its calls, scents, scent blockers, etc.
Keep in mind I live in a state with a 4 month gun season, and I get an additional 16 days on that because I bow hunt, so from Aug 15. to Jan. 1 I am pursuing deer.
My experience is that grunt tubes,bleat cans and rattle bags work best in the rut, with rattle bags especially in late rut. Its not so much do these products work or dont work, its more what time of the season you employ them.
Outside of rut, I have had some success with grunt tubes but these have only worked well at making a walking buck stop, and I have been able to get bucks to grunt back at me who were within a close distance and responded to a throaty buck grunt.
I dont think they work at "calling" a deer to you, like a duck or turkey, I think its more grabbing their attention and making them curious to come check out where you are, if they are in the area. Specifically when the bucks are moving more and are less cautious during the rut.
I think this again emphasizes the need for scouting and setting up in areas with high traffic where the deer are moving, no can, tube or rattle will attract a buck that just isnt in the area.