I got a nice WL book from a yard sale and didn't notice that the first piece of paper (not the title page) (a flyleaf?) has been carefully torn out.  Do you think this is just unpostable or trash?

I'd say postable.  Missing text pages make it unpostable, but a flyleaf can be written on.

I think there's a thread around here that says that.

It is postable. Non-text pages can be missing. You may want to neaten up the edge, if possible.

What they said   If your book is in otherwise good condition, it is postable.

Great! Thanks a lot. I assumed it was unpostable.  Maybe the written inscription was too personal?  Anyhow Thanks. teri

Some members also worry that any handwriting will get their book RWAP'd (not just the 'on text pages' part).

It's postable, but it never hurts to PM the other person before sending.