and I'd like to know what situation that I will rejected. (or what condition should I meet to acquire the WP blue book)

If you continiue to work if your WP application is rejected, then you are working illegally.

And lets assume you have been issued a single entry Non-imm B, then after 90 days your visa woud be invalid as well, and if you continue to stay in country, you would be on an overstay as well

and I'd like to know what situation that I will rejected. (or what condition should I meet to acquire the WP blue book)

If you continiue to work if your WP application is rejected, then you are working illegally.

And lets assume you have been issued a single entry Non-imm B, then after 90 days your visa woud be invalid as well, and if you continue to stay in country, you would be on an overstay as well

Got your point, thanks.

but I mean generally speaking labour dept will approve the W.P. for a reasonable position, will they?

This concept of working while your WP applicant is still under consideration is arrant nonsense.

Although not disagreeing with the words on the paper, if you go an talk to any labour Department office, you will find they tell you it is permissible to work while "under consideration" and have seen passports stamped as such "Under Consideration", also believe one of the posters is correct in saying you get a letter as well from the labour office to this effect.

So it appears from a practical stand point it is not "arrant nonsense"

There's no mention of WP in passports.

The "under consideration" stamp you have seen is for extension of stay based on marriage where a committee in BKK will make the final approval.