I completely agree with that stance. We should always be careful, even with ministries that we know and trust- because first of all the best of us can have huge weak spots, and secondly we always have to be Bereans.
I love Chuck Missler's take on this. He is ALWAYS cautioning people listening or reading to check the scriptures for themselves, to see if these things be so. He is with the Lord now, and I love his teaching, but there are just a few spots that I'd quibble with like with any good teacher.
Lee is an excellent scholar, but I don't agree with him on his take on Babylon, and I think he borders on the weird when it comes to his black thread teaching. He has an unusual take on timing of the Seals, Trumpets and Bowls, that they are somehow both progressive and simultaneous which I've gone over and don't think I'd agree but short of those things, he's been great on everything else.
Edited to add, I am more focused on what they teach, how it stacks up against the Bible and how it compares to conservative dispensational teachers overall.
People I respect like Jan Markell and Gary Stearman rub shoulders with some that I consider way beyond acceptable, while their own teaching remains good in general.