I check the Sandbox this way.
1) You must be getting links for the keywords you are optimizing for…as an example, let’s use “online casino”
2) Check your ranking on the Google data centers on a site like http://www.mcdar.net/q-check/datatool.asp by entering your site URL and the term “online casino” (without the quotes)
3) Next, using the same site enter “allinanchor:online casino” (again without the quotes).
4) Compare where you come up in the normal search and where you come up with the allinanchor search. If they are quite far apart then you are sandboxed for this term.
As an example, one of the keywords I optimize for brings our site up as number 16 allinanchor, but number 622 by typing in the term alone. Other terms we come up in the top 20 allinanchor and don’t show up in the top 1000 typing in the term.
You should also be aware that the sandbox keywords differently. If you try to optimize a site for a term with little competition (eg: “Click2Pay Poker Sites”) you won’t be subject to the sandbox, whereas optimizing for “Poker Rooms” will put you deep in the sandbox.