Going to a play is usually hit-or-miss; even when you attend a performance by one of Chicago's celebrated companies, the script might be a dud, or the acting uneven. ShawChicago, though, is always a sure thing. They do only a handful of shows a year, and most are staged readings, but the plays (since they're by George Bernard Shaw) are guaranteed terrific--smart and funny--and the performances are so consistently skilled that you forget you're not watching a fully staged production. See for yourself: You Never Can Tell is at the Ruth Page Center for the Arts until next Monday.