plastic frames in a hive not accepted

I was called by a great couple in Ojai who had bees in their backyard, which were acting "weird". They wanted me to come out and take a look. When I arrived I suited up only to find out the bees had absconded. Another beekeeper had advised the couple to use plastic foundation. In the photo's you can see for yourself how the bees "accepted" the plastic:

It's clear: they didn't!