Being approached by scam artists, pickpockets or thugs seems to be a common occurrence in what I read. What are the pros and cons of carrying a whistle to blow when one gets into a situation where the perps seem to be unwilling to move away from you or to leave you alone when asked? I boiught a couple of metal whistles at Wal-Mart.
Whistles are completely unnecessary, and won't help you with against pickpockets. A good PP is well dressed and polite, if you get robbed by one you won't know it happened until he/she is long gone. Your best defense is to follow Rick's money belt advice and carry only a day's worth of spending money in your wallet or purse.
Michael is correct. You don't need a whistle. All it will do is attract a lot more attention. We have spent nearly 300 days in Europe over the past ten years or so with serious problems. We take a number of normal precautions. Just don't make yourself an inviting target and you will be fine. If necessary, a good, loud, firm no generally takes care of the situation especially if you move away from the situation rapidly.
I agree with the 2 replies above, a whistle is probably going to label you as 'tourist' faster than your accent and perhaps make matters worse. I travel alone alot and have never had a problem, touch wood. If I am in the situation you describe I just say 'no' firmly and walk on quickly making it quite clear I am not interested.
I agree with everyone so far -- I'm a middle aged woman who has been to Europe 5 times, Italy included. Sometimes alone or with only my sister of similiar age. We have never been seriously accosted or threatened at all. I actually find some of the panhandlers entertaining -- particularly in Venice! But I live in San Francisco and like to compare them with what I see at home all the time! Just look confident, no need to be afraid or anxious. Rick does spend a lot of time -- particularly in his Rome guidebook - warning about pickpockets but I think he just wants us to be forewarned and prepared to blend in with the scene. Then we can relax and enjoy.