Hi there! I have had 2 permanent retainers for about 12-13 years. They are like you described, bonded to EACH tooth in question (4 on top, 6 on bottom). I will say that the glue has never interfered with the hygiene of my gums or teeth, but it IS a pain in the butt to floss around all of that garbage, and it does seem that something always gets caught in there that needs to be flossed out.
When I don't have access to a toothpick, I find myself constantly working my tongue over them trying to dislodge a bit of food. Sometimes I rub my tongue absolutely raw trying to get at whatever it is. I really wish I could have the type that is only bonded to two teeth- I think it would make a big difference.
Lately I've had some tooth movement in my back teeth, but the front ones (the wired ones) have stayed in place beautifully.
I guess each type has it's advantages & disadvantages, but I don't think your dentist has to worry about hygiene being an issue. Heck, any type of retainer is less maintenance than braces!