Scope is fogging up and appears to not be clear. Tasco 3x16

Fog in the scope means moister inside. You can try and dry it out, take the rear lens off and using a hair drier heat the tube and the lens separate. Do not blow air inside it may damage the cross hairs. You can try and pressurize the tube so it will not happen again. You will need a large clear zip lock baggy the biggest you can find. Once your scope has been heated with the hair drier. Put the scope in the bag. and try to draw out all the air inside. You can use a Vacuum cleaner. if you get enough air out you can reinstall the adjustment lens on and the tube should stay in a vacuum for a season or two. You can also put vasiline on the threads to help seal the vacuum. You can also try to use gas, you can use gas from a paint ball gun cylinder to pressurize the scope. Put the scope in the bag pressurize the bag and reassemble the scope with the gas inside.

Fog in the tube means that one of the o-ring seals has cracked and let the nitrogen gas out and let damp air in during the warming and cooling cycles of use so the sight would need to be disassembled to check for damaged seals and recharged with an inert gas
seals you could do yourself purging and recharging very difficult