Not sure if you've done this, but register at anglersatlas.com, they have a lot of free maps of lakes with depth charts and everything. Might help you avoid the 10ft lake trout spots...
Otherwise, checking yourself is sometimes the only way to know what's in there.
My brother and I fished Dymond Lake for years and brought home monster walleye almost every outing. Strange because this is a small lake.
The MNR stopped us one day, and asked where we'd caught the fish. They accused us of lying when we told them the walleye had come out of Dymond.
"There's no walleye in Dymond", they said. "We've been stocking that lake with specks for years".
We eventually managed to convince them they were wrong.
Moral of the story, no source can be considered 100% correct unless you go there yourself and fish the lake.