My first question would be what does 100% success mean?

If it means they have been profitable every year then that really isn't much of a claim unless we know how profitable.

The wording though seems to imply that every pick is a winner which is so unlikely that saying it is impossible would be acceptable.

The only way that could even come close to being true is if the picks are all very low volume such that the newsletter itself could cause the stock movement. This would only be a success on paper or for the publishers of the newsletter who could act before distribution. For the actual subscribers it might lead to paper profits but any attempt to crystallize the gain would eradicate it.

I saw this advertorial on tradingmarkets.com and thought it looked kind of cheeky.. How is it possible for stockpicking.com to have 100% success.?

I'm curious to know if anybody has had any dealings with them and can vouch/disvouch for what they're bragging about.

The StockPicking.com newsletter reports that it has 100% successful stock trading alerts reported in 2009. Known for its phenomenal results, the StockPicking.com online newsletter has been challenging traders and investors since 1998 to put them to the test with a 30 Day Free Trial. The newsletter states its success comes from finding catalyst driven stocks, riding the momentum, and taking profits when the momentum or fundamentals change.
http://www.tradingmarkets.com/news/press-release/ibm_stockpicking-com-trading-alert-newsletter-reports-on-ibm-earnings-714704.html