What happens when the Thai wife spends more money than you have, maxing out her credit card and buying other things on financial agreements without the husbands consents?Is the husband legaly responsible for the debts in such matters?

I haven't checked with a lawyer but from what I have heard: Yes, you are legally responsible for your wife's debt if you are legally married. You can sue her to get money back (ha ha) but nothing takes your responsibility for her debt away.

I'd like to hear someone who actually has checked with a lawyer, is it true?

Interesting question. I often have to co-sign for financial transactions, like loans or standing guarantee for someone. I suppose that is not done for nothing.

But what Mikeydea says is true in most countries, you would be responsible but could have regress on your wife.

You can find more information on this subject here:

http://www.thailawonline.com/images/thaicivilcode/book%205%20title%201-3%20thai%20civil%20and%20commercial%20code%20.pdf

Chapter IV on page 5 deals with the property while married. This are the translations of the actual Thai law, be sure to read all articles and ask a lawyer for advise about their actual meaning.