Those are the classic ones. But could also be inadequate/missing blocking/bridging, overloaded condition, etc … I take things on a case-by-case basis in formulating a professional opinion.
JMO & 2-nickels … 
Hi Guys,
I’m rather late on this discussion and enter only to confirm earlier statements ‘opinions…everyone has one.’
As stated or eluded to in these posts, HI’s are not experts (brain surgery requires a brain surgeon.) So, any HI who views this and does not question such technique maybe ought to re-think it. What I see in the picture is not reasonable - from my perspective (having only built a couple of homes in my lifetime.) Stiffness in a member directly correlates to strength and I just don’t believe this floor system would be rigid. If I were the prospective buyer of this home I would have my Realtor offer an “Open House - with all you can eat buffet.” About thirty minutes into this buffet participants would find themselves on the basement floor - I don’t care what the manufacturer recommends!
I will make one exception to this: if the flanges of these engineered I joists are a stress-in-bending MSR flange and the floor was not spongy, I would not worry. (MSR=Machine Stress Rated.)
We don’t have to be 100% correct in our judgments - “my” job as a HI is to point out concerns, as one who has studied all the building disciplines. It is the option of my client to followup on my recommendations. And, I will always play it safe by pointing out things that “may” be a concern, for obvious reasons. This of itself has offered substantial benefit to my client.
