Trustworthy, not a problem. Consistent, another matter.
Two who have been around a long time - ten years plus - and I believe to be trustworthy are Steve Lewis Hamilton and Guy Ward (works under the name "The Mathematician"). One of them I know as I used to supply him with some of the data I download daily from the Post's website. The other I have never had any personal contact with but a friend who has speaks highly of his honesty.
re consistency, I've always been ambivalent about professional tipsters. On the one hand, if they were really good, why would they bother running a service rather than simply betting? On the other, to stay in business for any appreciable length of time like the two I've mentioned, I'd assume they must have some long term clients and not simply a constant flow of new ones. And if the assumption of long term clients is right, presumably the services must deliver well enough for such clients to remain.