Generally speaking, your presence at this establishment will be a source of entertainment for them. Even though I don't trust anybody, I'm also aware of the fact that most locals over-estimate their own cunning and wile, i.e. they aren't anywhere near as crafty as they think they are. And some of the most bald-faced liars you ever met. The big question is how sharp are your street smarts? The key to being safe in that snakepit is seeing the danger long before it gets to you. If a stranger approaches me - at any time, in any place - I politely tell them to get lost. Now, if some punk were to pull a gun on me, I'd hand over whatever I had on me, since it's generally never more than a few thousand pesos. You can have that, buddy. Also, I never carry credit cards or extra cash unless we're going to make a big purchase; and in that case, it's straight from the taxi into the shop.
This. The vast bulk of your negative interactions with Filipinos will be petty, transparent, or downright retarded attempts to part you from smallish sums of cash. That's not to say that violent robberiesd don't happen - the place just next door to my business was done over last month, but then again I live in a part of the Philippines where the police believe their job involves (a) fobbing off the public with excuses and (b) napping. Manila is a different ballgame - different class of criminals and a different class of policemen, and it can be hard to tell the two apart. Broadly speaking, the hardcore criminals will target lucrative opportunities (as goose egg said) and probably aren't going to be interested in a sausage shop.
Small word of warning: Filipinos are endlessly coming up with ridiculous business ideas that are guaranteed not to work. Their main purpose, usually, is to get the rich kano to "invest" some money, which will then be spent on cellphones, a new tin roof, cockfighting, etc. In a few instances it may actually be put into the "business", but for any number of reasons the business will (predictably) fail. Even if you maintain control of operations and finance, you'll be faced with a predatory bunch of regulators, taxmen, and assorted rubber-stampers who will nickel-and-dime your business to death. Most businesses keep double books because they'd be out of business within a week if they didn't.