Well, a lot of things rely on evidence; even the run-of-the-mill punch you and run away and you can't find the fella.
However, I would like to correct a common layman misconception that touting is only applicable for fake goods - they usually think of touts wearing trench coats pedding fake watches in Orchard Road.
It would be useful to take a look at the following:
Touting for business
32. Any person in any public road, public place, place of public resort or vehicle on a public road who, in connection with any trade or business (whether or not carried on by that person), solicits any other person persistently or in any manner as to cause or be likely to cause annoyance to that other person shall be guilty of an offence and shall be liable on conviction to a fine of not less than $1,000 and not more than $5,000 or to imprisonment for a term not exceeding 6 months or to both and, in the case of a second or subsequent conviction, to a fine of not less than $2,000 and not more than $10,000 or to imprisonment for a term not exceeding one year or to both.
From the above, we can see that there is no requirement that the goods need to be fake, or need to be branded.
Small Claims? That depends on what you are aggrieved about. If it is because you paid too high a price for something, then like the usual carrot chop SLS shop situations, you do not have a legal right. If there was misrepresetnation (Buy this S$500 speaker from me because it can do A, B, C) and it ends up that it cannot, then yes, you have a cause of action under Small Claims. Do make sure you can find the person/entity who sold you the thing though. If they sold you from a van, I'm not sure if you can even trace a contracting entity.
You are right about the police bit. In most, if not all of the cases of minor crimes that have been brought to my attention, more often than not, the police give wrong information (they can't distinguish civil from criminal action) and they will not bother to take up your case until you lodge a Magistrate's Complaint (putting an obstacle in your path in the hope that you drop your action).
Under the Business Registration Act, you need to register so long as you run a "business", which is defined as including "every form of trade, commerce, craftsmanship, calling, profession and any activity carried on for the purposes of gain". There are exceptions to this rule in the First Schedule in the Act (only craftsmen, licensed hawkers, taxi drivers, trishaw riders, sampan rowers and farmers).
In my view, they are not so much riding on loopholes in law, but loopholes or lapses in enforcement. I believe the laws are there, but there is insufficient enforcement.
