'he was a really nice bloke and explained exactly what the guild does and what I can expect to gain from it as a member.'
Of course he was a really nice bloke his a salesman. The opportunity of pound notes can make anybody be really nice.
In my opinion most trade organisations are only there for your money and it was the Guild of Master Craftsmen that brought me to that opinion. Many moons ago I had a call from them and said that someone had recomended me, of course that makes you feel good and I accepted him to visit. I looked forward to his visit, I thought yeah what an accolade a master of my service, proven to be up there with the best. Anyway he came (he was a really nice bloke aswell) spent about an hour telling me that you could only get this recognition through recomendation (this was about twelve years ago), gave me his pitch, showing me his book, loads of pages about what it will bring to your company and several pages, showing you how your advert could stand out with the Guild of Master craftsmen logo on it, well this page had a dozen or so adverts on it (as you would get in a normal directory, i.e. yellow pages) and on the page, one advert had the logo on it which makes it stand out from the others. The logo could have been a black blob (as it would have been at a flashing glance), that would have stood out aswell. I asked him who recomended me and he told me that he could not disclose that info, that made he a little suspicious because I felt that if someone had recomended me, then they wouldnt mind me being told who it was. By the end of it he couldnt avoid having to tell me that it would cost and then it was about £500, so I showed him where the door was.
I am in no way trying to say that trade organisations do not benefit a company and if you was looking to join one then I would say as others have, join one that clearly represents your trade. You will still get the recognised logo for your van, media etc
The best way to show that you are a pro is to do a good job and give a good regular service, that way customers will find you through recomendation, it will not cost you anything financialy and you will soon have more work than you can handle. With or without a trade logo.