i just had engineered hardwood floors installed today. they are glued down to the slab. there are some pretty sizable gaps between the boards, most are about the width of a dime, some are a quarter. I can see the raw wood of the tongue between the boards. Is this at all normal? I feel like it totally unacceptable.

pics: https://imgur.com/gallery/KxJVaK7

Engineered plank is made to have minimal expansion so these gaps will need to be filled with colored putty to look OK. Glue down flooring usually needs to be held in place with clamps as the flooring is laid so gaps do not develop before the glue has set. It takes more labor to install with clamps vs. using blue tape to hold the rows together, but a much more professional looking outcome will be produced.

I agree with you. It is unacceptable.