My turtle (Kreffts shortneck) never stinks- his tank has the correct filtration and water changes = no smell, and when he's handled he never smells either.
Turtles are very expensive and can be time consuming to keep, I can tell you that much! They end up having pretty specific housing requirements (they grow pretty large, even the smaller species), require certain lighting if kept indoors (I used 10.0UVB tubes, replaced every 6months- $50 per bulb), heating (Water and basking area), very powerful filtration (good quality, high powered external canister or sump filters).
My boy (now 4yo) is in an outdoor custom fibreglass spa bath with 700L of water. The filter for this cost me about $500 (pump + filter).... He only moved into this at the start of this- before this setup, he was in a 4ft x 2ft x 2ft tank full to the brim (above tank basking dock), all of which requires 24/7 heating during the cold months (dependent on location and species kept), 24/7 filtration (with large tanks the wattage of the filters obviously increases = more power used), lights during the day etc..
Providing a good quality diet can also be tricky/time consuming, as they're best off if they receive freshwater foods such as fish, shrimp, aquatic plants etc.
They do cost a lot more than snakes, and are more time consuming, but at the same time they can be very interactive and as mentioned above they seem more sociable. I love my boy
