While I don't have a caddie for the majority of my rounds, I have used caddies on many occasions, and haven't had many bad experiences. In fact, I've had many outstanding experiences. Caddies have significantly enhanced my experience for many rounds of golf.
In the pro looper category, I've had numerous caddies that not only provided all of the baseline services, but also provided terrific advice on ideal lines, trouble spots, green reading, etc. To avoid potential conflicts, I always ask what yardage the shot will play (sometimes clarifying if they are providing the actual or effective distance), and choose my own club accordingly. Nobody likes a caddie they just met trying to pull clubs for them, but I've only run into that once or twice and nipped it in the bud without an issue. I'll also ask questions such as whether a run-up shot is appropriate, or whether certain features can be effectively utilized. Of course, it's still up to me to execute, which sometimes I do and sometimes I don't. I've found that many caddies are good players and/or students of the game, and therefore provide some pretty darn good advice most of the time.
I've had plenty of young kids that are just learning to caddie as well, in which case I'm happy just to have someone to carry my bag and rake bunkers for me. It's nice to put a few bucks in a kid's pocket, especially when they are part of programs such as the Evans Scholars Program, which has sent thousands of deserving kids to college. There's a wide spectrum of caddies, and I've found just about all of them quite helpful.
On several occasions, I have had caddies that knew quite a bit about the history and architecture of the course. While this is a bonus (not an expectation), it is terrific when you have someone showing you around in addition to (or in place of) a member host.
I've had good caddie experiences at resorts (very recently had one of the best caddies ever at Pinehurst #2), well-regarded private clubs (perhaps the best caddie I've ever had was at Sleepy Hollow - he made my round and my overall experience outstanding), and smaller clubs around the country. In my recent (first) trip to Scotland, I used the same caddie for all of my rounds in St. Andrews. Having grown up there, and worked 35+ years on the links, he knew every inch of ground on the courses and more about the history than just about anyone on this site. I'm not a rich guy, so the cost wasn't an afterthought, but it was the best money I spent on the trip.
I could go on, but I won't. I just don't get the anti-caddie sentiment that seems so prevalent here, and thought I'd put one mark in the positive column.