How can I know if a hybrid plant (or a cultivar) is not going to attract bees...
What a good question! Unfortunately there isn't an outstandingly clear answer.
Pollin is an essential food for bees, butterflies and countless other less charismatic insects. Pollination is essential for the ongoing life of most herbaceous plants on this planet. Serendipity! As your question suggests, we are messing with this equation and the results are not really linear.
Pollinators can find nourishment from many hybrid flowers. These plants aren't necessarily less healthy for pollinators but many of them have been bred to have stunted or missing stamens and pistols - for aesthetic reasons. Clearly these plants have nothing to offer a bee or butterfly.
Sometimes the hybrid flower has been bred to assume a different shape and the pollinating insect has trouble accessing the "goods". If the hybrid flower looks significantly different from the parent flower it may be too different for a pollinator.
We don't have a list of pollinator friendly hybrid flowers but if you keep these two thoughts in mind when you purchase your seeds or starts next year they should help you choose among your favorites.
I hope this information is helpful. Please contact AaE again if you have further questions.