There can be many delicious smells that come from ovens when good things are baking, cooking or broiling. However, ovens can also smell funny or bad, depending on what was cooked, if food spilt or dripped during the cooking process, or several other factors that may result in a strange or bad smell coming from the oven.
If the oven is new, it may smell a little funny the first few times it is used. This is typically just due to leftover residue from the factory that is burning off during use and is normal. Make sure you remove all packaging material from the inside and outside of the oven, before use, to prevent tags, stickers, paper or other packaging from melting while the oven is in use.
Food often drips during cooking or baking, such as pies that may sizzle and drip, food that bubbles over, pans that are too full and overflow or even grease that drips during broiling or cooking. Food then burns onto the bottom of the oven or on the racks, and this can start to smell bad. Clean the interior of the oven, including the racks, pans and the oven bottom, with a damp sponge and a few drops of dish washing liquid then wipe it down with a damp cloth. You can also use an oven cleaner to help remove food spills or a steel wool pad to scrub stubborn areas.
Look in the bottom of your oven and you may find items that fell during cooking and have possibly melted, such as plastic cookware, bake ware or utensils. Allow the oven to cool completely then scrape as much of the item free as possible with a rubber scraper or the flat edge of a knife. Use a household cleaner that is labelled "oven-safe" to remove the residue. Note that if items get burnt onto the heating element, it may need to be replaced.
If the oven is a gas range and it smells suspiciously like gas, turn the oven off immediately. Leave the house and contact your local gas company or fire station for assistance as there may be a gas leak, which can be very dangerous. Do not try to fix a gas leak yourself.