Drugs at Skidmore are certainly present, but mostly if you want them. Aside from drinking alcohol, marijuana is the most popular/common drug around campus—smoking is certainly not limited to the weekends at Skidmore. Skidmore has had a "stoner school" reputation, and it warrants that reputation to an extent; however, if you do not want to smoke pot, you're not forced to by any means, but you will certainly be around it to some extent (factors include: the friends you choose, the neighbors you have in your dorms/apartments, and the weekend activities you attend). Other recreational drugs on campus include cocaine, shrooms, and ecstasy. Some students also choose to take Adderall or other "study drugs." All of these drugs are less apparent on campus, but they are certainly present if you want them. Drinking is most common on campus on the weekends (Thursday through Saturday), and is probably the most popular form of partying on campus.
Campus Safety and the administration are not blind to the drug use and drinking on campus, but they are not necessarily looking for it, either. The Alcohol and Other Drugs (AOD) policy was recently revised to make it a cumulative point system (you gather points for certain offenses throughout your four years; if you rack up enough points, you will be suspended). However, the only way Campus Safety will really get you in trouble is if you are being extremely obvious in either drinking/parties (loud talking, music, noise complaints) or smoking (smell).