This is very common in many airports around the world, someone who is trying to make a living by driving people form the airport and offering their services. Usually they are tourist traps and they will try to take as much as they could from you, unless you know how to deal with them.
Their services vary, they can be taxi drivers, they do offer accommodations (they have some sort of agreements with cheap hotels where they get some sort of commission). In some places, they can be pimps as well and they might start talking about their lovely friend who is a female and so on. Last but not least, they can offer drugs as well. I do not generalize all of these services to all of them, it depends on the country and the person, some of them are just honest people trying to make a living.
If for some reason one decides to use their services, they always start chatting about if it's your first visit to the country, or whether you speak the native language, etc. After that chat, they will try to go as expensive as possible depending on how they see you, also they will be able to know what kind of service to offer, should they offer you just the ride, or should they go beyond that!
Are they to be avoided at all times? Mostly yes, but sometimes no. Avoid them if you are new to the place and does not know the way around and do not speak the language, avoid them at all costs. If you are familiar with the place, and familiar with the people and rules there, they could be a good last resort when there is no taxi. Sometimes they offer services cheaper than the metered taxis if you know the way around. I have used them myself in Indonesia and in Saudi Arabia, but I speak both languages and I know my way around these countries, but for sure I will not use them anywhere else.