| scandalmonger(noun, gossip, nuisance, informer, tattle) |
| scopophiliac |
| scrutinize(verb, examine, discover, look, watch) |
| secret service(noun, expression, plant, agent, operative) |
| secretly follow(verb, expression, examine, case, discover) |
| sergeant(agent, spy, informer, reporter, gumshoe) |
| set eyes on(verb, expression, idiom, examine, discover) |
| shit |
| shoofly(agent, spy, informer, reporter, gumshoe) |
| shop |
| sidewalk superintendent(expression, gossip, nuisance, ferret, nosy) |
| sightseer |
| sleeper(noun, plant, agent, operative, informer) |
| slewfoot(agent, spy, informer, reporter, gumshoe) |
| snuffle |
| spook(noun, plant, agent, spy, operative) |
| spot(verb, examine, discover, watch, scrutinize) |
| spotter(noun, plant, agent, operative, informer) |
| stake out(verb, expression, examine, case, discover) |
| tabby(noun, gossip, informer, tattle) |