The word is "most."
Most bareboat-charter companies are able to hire a skipper for you at most or all of their bases and most can also find an instructional skipper, should you want to brush up your basic sailing skills or acquire cruising-specific knowledge. Most of the time it goes well. You not only pay the skipper, but are also expected to provide a cabin on your boat for him/her as well as provisioning. This scenario is especially true of, but not limited to, charters in the Caribbean. I am of necessity speaking in generalities, since there are differences from company to company and from place to place; you can get specific information by linking to the Web sites of charter companies with bases in the Caribbean/worldwide and U.S./Canada through sailmagazine.com at Charter Cruising:Charter Companies.
Charter companies deal with skippers they have come to know and rely on over time. The world of chartering is small, and reputations, good and bad, are pretty much out there. The upshot is that the skipper who greets you on your chartered bareboat is likely to be knowledgeable and personable and, often, to end up as your new best friend.
Sometimes—rarely, but sometimes—this doesn't happen. We recently heard from a reader who, with his wife, chartered a boat in the Caribbean and requested a skipper who could help improve his sailing skills as well as act as a guide to the islands. Unfortunately, they were not only bitterly disappointed, but were alarmed by this gentleman's unsafe sailing practices.
I asked some charter-company people whether this could have been prevented. If you're hiring a skipper, they told me, you can ask to have a phone conversation with the skipper before you ever leave home. If the conversation isn't satisfactory, you can then ask the company to suggest someone else—and then be sure to do another telephone interview.
But suppose you've spent a day sharing the relatively small space of a typical charterboat and find that you and the skipper are seriously mismatched, and you and your companion(s) are miserable. What do you do then? Keep in mind that you're a valued client, not an indentured seaman, and contact the charter company immediately (you can reach them by cell phone or VHF, or from a phone ashore). Explain that you're finding the situation untenable and explain the reasons for this. At best, the company will be able to find a replacement skipper; at worst, you can ask the skipper to find a place for you in a secure and pleasant anchorage where you can spend the rest of your vacation enjoying the setting, the scenery, and the island without him or her, and arrange for the company to send someone to fetch you and the boat (if you're uncomfortable sailing it yourself) and return you to the base when your charter time is up. It's not the same as sailing, of course, but it can be a more than pleasant time, and you can enjoy your floating hotel room.