Ask them for contact details of other "franchisors" and ask several of them if they are happy with everything..
From their website, it would appear that you are not being offered a "proper" franchise so find out exactly what you are getting for your money (in writing) and get it checked over by a lawyer familiar with Spanish law before parting with any cash.

I have already sent a PM to rob along the same lines as your post mibut, but have now looked at the Bars In Spain website. Some interesting reading, but am I missing something?? It looks to me as though the "franchises" are for Estate Agencies, specialising in selling commercial properties, including bars? Have I read it all wrong?