Must admit I'm not actually bothered about identifying / contacting living relatives.
I've encountered information on trees where people / events I know ARE mine haver been adopted or modified to others.
As (I hope) I check things out quite carefully myself, usually finding all possible people, drawing out a large chart and entering in all of them, over several decades (censuses etc.) to help eliminate them, I've three times found situations where people have "adopted" someone of mine, despite having to twist wives and children ( or simply not noticing /checking that names of wives and children were not in the censuses they quote, the same!) and high-tailed them off to their tree, providing them with entirely different descendants!
This doesn't especially worry me, I know where I've got proof, and I'm pretty certain that they haven't been as meticulous, or they wouldn't have ended up where they were, but it is a minor irritation, and evidence often of sloppy research ("Oh, here's a Thomas C of about the right age, says he came from Ireland .... doesn't matter he's got a different set of children, living in a quite different area of the country, with a different wife, in the previous and the next census - I'll have him!"). But it'll always happen.
I would imagine that any "professional" researcher may not actually be as thorough as many amateurs, as they will have to limit hours spent, even though they may have some access to richer resources than many of us have, and I would also imagine if they have sense there will be some caveat that they are making a "best guess"/" best fit" from the original information provided from the person employing the professional.
I would also imagine that there will be less satisfaction in being presented with a tree that is all done and dusted, than knowing that you have unearthed everything yourself, or of course, with guidance from like-minded enthusiasts on here, diligently.
I was once provided with a copy of a "Researcher"'s tree by a relative, and almost immediately spotted two errors, which allocated a wrong set of parents to each of two ancestors... which means the whole thing was a bit ridiculous further back, but someone, in all good faith, had paid for that! It took me a while to decide if I should point this out, I did, under the "an alternative line which I think is more likely" , to be told "but I paid for that, so it must be right"!!! At which point I gave up. It wasn't me wasting my money.
