I have free range chickens.
Yes, they forage in the flower garden....I have a few tricks for new plantings, but once they're settled, they leave them alone--except for a few varieties...can't get astribile without fencing!
DE is great for getting rid of bugs, but be careful how you apply it, as it kill the good bugs too--including bees that come to polinate your plants!
My garden is fenced off...but don't underestimate the power of chickens to kill bugs. By keeping the bug population down around your garden, it does help with the bug population in your garden. Same goes for the ducks and slugs--I've now gotten to the point where I'm excited about finding a slug so I can give a treat to the ducks!!!
During the "off season", my chickens and ducks have free range in my garden.....They fertilize it, till it, debug it, and keep the weeds down. Makes for a GREAT start the next season.
Chicken tractors between rows is a great way to continue the "off season" process....
When I clean out the coop (I use the deep litter method)- I throw the bedding into the garden and then till it under after about a week. Then I plant another week or so after that- no problem with "burning" of plants, but it's not like I put inches of bedding on the dirt either. For the raised planter person....in the fall add your coop bedding on top and then work it into your soil (or let your chickens do that part!). You'll notice a big difference in the next spring.
I could go on.....chickens are still a great thing for gardens.
(oh-yea....coops shouldn't smell, if they do--you're doing something wrong, and very often it means you have too much water/moisture)
Sandra