I totally agree with what your saying, I met some really arrogant DMs and Instructors who are just as you describe, they give the good ones a bad name. Some of them seem to be in the job just to pick up women.
In my opinion what makes someone good at the job is realising that they don't know everything and make an effort to keep learning, I've found that you can learn from customers as well as other professionals.
One of the biggest problems guides have is customers turning up with qualifications that their instructor seems to have just handed to them, I once had a customer who wanted to do his advanced OW, I told him I wanted to get him in the water first and do a quick skills check with him, he hadn't been diving for a couple of months and only had 6 logged dives, he refused to take his mask off, apparently during his ow course he panicked each time he tried so his instructor allowed him to carry on without doing so then qualified him.
I spent a whole day with him in the water updating/ re-teaching him skills and in the end he was taking his mask off without a problem. I told him to report his instructor to the relevant training agency.
Often guides end up being instructors and nurse maids and for no extra pay and it often comes down to poor training and bad instructors in the first place.
Most good guides soon pick up whether their customers are properly trained or not and if they're working at a good dive centre with good management then they will change the group structure accordingly sometimes splitting the group and bringing in an extra guide.
However, there are some downright nasty managers out there who hate spending money and if the guide makes any trouble for them (read that as doing their job properly ) they will soon be replaced, there's always someone else willing to do the job, usually the rubbish dive guide you were referring to in your earlier post.
When work has been quiet I've been called by dive centres to do some freelance work, on arriving at the centre I've found rusty O2 kits, old un-serviced rental gear, no first aid kits and they want you to take a group of up to 10 customers out with mixed skill levels, some with over 500 logged dives mixed with freshly certified ow divers. I've just told them to forget it and walked out, usually with verbal abuse ringing in my ears from the manager.
What I'm getting at here is that the customer has a responsibility to themselves to thoroughly check out the dive centre first, what is their equipment like? What shape is the compressor room in? What size groups do they take out? Do they ask to see you cert card and log book? Are they genuinely friendly? Can you meet your guide first?
Most problems with bad guides can be avoided by doing this as good dive centres with almost always have good guides, unfortunately from my experience at the counter too many customers are more concerned with a cheap deal than with the above concerns.
On the point of tipping it is always much appreciated by the guide or instructor however when working at resorts it is a rare thing and where I was, not expected. The customer base is from all over the world and tipping is not in the culture.
In the end I'm just pointing out that no matter where you go or what you do in this world you'll always find ********s on both sides of the fence.