zap7

I don't know about IAH, but I've flown TK from MIA twice in J. In MIA you could NOT use mobile Boarding pass, and they did NOT have TK staff, but contractors at the checkin desk.
I has unlucky and got a grumpy Agent who didn't even know the rules: "Sir, you can't take two bags with you"
"Oh, pardon me, I think with Turkish Airlines, Business Class passengers may take two cabin bags. It's so confusing these days with different rules for different carriers… Let's see, right here on the Reservation it says 2x cabin bag…" (said this in a really polite way, but she had been grumpy and unfriendly from the start...)
"OH, you are in fact right, sir. BUT I HAVE TO CHECK THE WEIGHT" - one of my carry ons was actually 11 kg (instead of the 8 kg allowed) and that was one of the only two times in C and another two times in Y where they took it from my - I did several hundred flights with this bag, usually at 10-12kg, 95% of those flights on European/asian carriers that only allow 7 or 8 kg. 99,5% of the time they did not weight it, and not once did anybody check the dimensions ( 1,5 cm / half an Inch too much in each Dimension for LH/TK/LX/SQ/AB).

Next time form MIA I had a very friendly Agent as usuall, and of course she never even asked for me to put anything on the scale.

I never, ever encountered any Problem at TSA or other security checks anywhere. I can lift that bag with one arm, get it in the overhead in a breeze, it fits perfectly, and in most planes the overhead bins is labeled inside with something like "load limit 46 kg" for one compartment that takes two of thoose bags.

in short: TK will rarely weight cabin bags (in C). IMHO the highest risk for this happening is US airports. If it happens, it happens at checkin. Watch the agents while you stand in line, If one seems unfriendly to other passengers or always puts all their cabin bags on a scale, Chose to write that important emails on your Smartphone when it's your turn and the unfriendly one would be the one handling you.... let somebody else pass in front of you and wait till one of the friendly ones is available.