Whilst it is true to say that one can be conned in any language, remember that, when someone talks to you in your own language in a foreign land, it may be very convenient but it is does not necessarily mean that what is said is by a professional or person qualified to state what is said.
In recent years there has been, and there continues to be, a major influx of people onto the Costa del Sol. Although they come from all parts Europe, the number of ex-pats from the British Isles by far exceeds any other group and is second only to the native Spanish. This may well be very convenient for all English speakers who do not have to be forced into learning any other foreign language, it is important to bear in mind that anyone speaking your own language is not necessarily qualified in what he is talking about or indeed what he or she is doing.
This is where the famous Cowboys begin to have a field day. It comes twice as easy for them to bamboozle another person with the same mother tongue. Once because that is the language they can do it best in and twice because they appear they can be trusted more than someone with a different background.
For example, just because someone calls himself an English doctor or lawyer it does not mean that they are qualified and, if they are qualified to do so in their own country of origin, it does not necessarily mean that they are permitted to practice in Spain. In addition to being commercially licensed, such professionals are required to register with and be licensed by the corresponding Spanish body of authority, the same as in the UK. Apart from possibly getting wrong advice from unregistered professionals, you also forego any right to compensation by the corresponding registering authority.
In the case where registration with a certifying body is not strictly required, it may be more difficult to distinguish between a qualified person and someone who is trying to lighten you by a few thousand euros. It is a bit too late when you discover that the mortgage broker or estate agent you trusted has diddled you out of a largish sum of money that you did not expect you had to pay.
Just because someone speaks English, that is not a qualification, it is not a guarantee of good service or workmanship (the contrary might be nearer the truth), most of all it is not a licence to trade with the English speaking communities. The only qualification charlatans have in common is the language.
Although this is a transitional phase in a growing market that has given the area a certain reputation, luckily things are changing. Those who have lived here for many years have learned to speak and write Spanish, obtained the correct Spanish licences for their profession, etc. and have become respectable professionals within their trade and their community. At the same time, it would appear that the new generation of newcomers to the Costa are more professional and sober in their approach to blend in with the working and business community.
There are still quite a number of Cowboys., Although many have gone back to their roots or are dieing of alcoholic poisoning, before you do businesses or part with your money, satisfy yourself that the person or company is qualified to do your job properly.
A mobile phone number is convenient, but do avoid doing business with companies or persons who do not disclose both a land phone number and an address (not accommodation address or P.O. Box). Ask yourself what do they have to hide? Why do they want to be able to disappear or hide? More importantly, avoid doing business with companies or persons who do not disclose their IVA Registration Number (if in doubt, ask for a copy of their registration certificate with the Tax Office or Hacienda). If you do business with them and they get caught as being illegal, you may well be held responsible too. It may be useful to ascertain how long they have been trading for, the longer the better.