New construction bathroom exhaust vents - tape won't work!
Looking at them from the ground (in this case from waaaaay behind the house as the roof was not visible from the ground) I could see the vent hoods on the roof.
The one on the right looks to be the dryer vent. That's a whole other issue because if you can't see it from the ground, how do you know the dryer vent is clogged? And then, what fun, when it is clogged you have to go onto the roof to clean it!
But I digress...
The exhaust installation kit looks very much like the photo to the right. That kit is available at any big box hardware store for under $25.
The key is the connector indicated by the red arrow. It is firmly connected with screws or nylon straps to the vent hood, which is itself attached to the roof with nails. The connector would be attached to the hood BEFORE attaching the hood itself to the roof.
The exhaust vent tubing (and I always prefer to see metal to flexible) should then be attached to the connector, preferably with screws. Once attached the 
gaps can be taped with aluminum tape.
Going into the attic one of the vents had already popped off the connection to the roof sheathing!
I had previously tested the exhaust fans. For all I know that test blew the connection off of the roof!
But what's missing?
The connector!
The hole cut into the sheathing is rectangular. The vent tubing is round. We have the proverbial round peg going into a square hole!
But secondly, tape is NOT how this installation should be done!
What is not visible in this photo, but the connection to the left is coming loose, another exhaust vent connection in the center of the roof is also coming loose, and one wonders if the dryer vent attachment, seen on the right, can be trusted. Only use will tell! If lint begins to collect on the sheathing around that connection, or if it looks to be coming loose, that means the installation was not done properly.
My recommendation: my client is out of the country and was not present at the inspection. So the report has to be very clear as to what the problem was with this installation. It is unprofessional at best, and ignorant of proper installation techniques at worst. Why employ anyone so ignorant of how to do anything on new construction? Installing a bath vent with tape? Really? Not acceptable.
Jay Markanich Real Estate Inspections, LLC 
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560
Good morning Jay. Not looking good! How was the rest of the inspection? Enjoy your day!
There were many things Wayne. As there often are with new construction.
Come on, Jay Markanich, you mean to say you would not blame the use of OSB Strand Board for the tape not sticking?
I will have to check with Red Green to see if common duct tape wouldn't be the better solution.
Tape is man's new best friend in construction.
OF COURSE duct tape would be the better solution, but not the BEST one, S&N! Screws actually work on OSB. And on connector tubes!
And Red Green would agree with my duct tape ranking.
You could be right, Harry, replacing even the fabled drywall screw (which is used for everything EXCEPT drywall...). Quick, easy and cheap is the new building best practice routine.
Jay Markanich Hey at least it was not duct tape. I had this exact same thing on my home when I bought it.
Gorilla Tape is the new duct tape!
Oh gee....homeowners always "assume" new construction is purrrrfect.....or...not...!
Don - spanning the globe! So, since "they" are in your neighborhood and my neighborhood, are we neighbors?
As it should be Fred. Strong, hairy, stupid. Why not?
You know what happens when we assume, S&D. Oh no! Did I just wax cliche?
Duct tape isn't the answer? On my, I have to reassess everything! Hopefully caulk is still the carpenters best friend.
It is, Stephen. But put so little on there that you can hardly see it.
Yeah, that's it.