Other than in that bit directly, in general you can look at the 'best plan' stage (via set option show long or set option show_best_plan on, search for 'FINAL PLAN').
Find the relevant PopStoreInd operator, look at the 'proj' (projection) for the worktable columns (some may be repeated so look at the distinct ones) and 'pred' (predicate) for the clustered index columns. You can also look at traceflag 201, but this will be a little more cryptic.
In general, under the reformat operator it will apply the filtering lookup predicates at point of scanning the table (ideally using a applicable index), but I think it could be the case that there are occasions when it may read the filtering predicate columns into the worktable along with the join predicates and cluster on both/all.