On the heavy and low end side but OEM pricing in the $300-350 range new suggests that the $100 price is not bad if bike
fits you and is in good shape. Look at tires for age related cracking and general wear, check for chain wear (google on
how this is easy to do), rusting on steel parts and dents in frame. With minimally or non-knobby tires it could be used on smooth
trails and roads. Probably should assume at least need for new tires, brake pads and shifter cables ($ costings in range of $50-80
depending on your source, if at LBS, add $20-40 for labor and $50 more for parts). If 2014 model then these may not be needed,
if 2009 it would be prudent.

To compare, frame should be notably better than Walmart equivalent and parts several levels above Walmart levels. Walmart
equivalents are in the $100-150 range new.

As stated, it's nothing fancy, but nothing to be concerned about as far as being "junk".
If it seems to ride "decently", it should be a good buy. Listen for noises that "shouldn't" be there, ill handling when turning 1 direction vs the other etc.
You might even ask the seller if they recommend servicing any parts. Some may not have a clue and some might suggest "it might be a good idea to...."

One thing I always do is service the hubs. To me, that's the part(s) that can get most expensive fast if it doesn't get needed service.

typical, brand new, actual sale price is $250 or so... this is a low-mid bike... some ok parts, double walled rims(at least on the current year model)

if it works well, and doesn't need all the things the other responders have mentioned, yu should enjoy it... as long as you don't leave it parked out in the rain... these lower end bikes LOVE to rust up and fail.

the only review i found on the bike was full of empty superlatives, and attributed things to parts that don't have a thing to do with reality... think: sales pitch.. not an actual review... the phrasing sounds like a bad Chinese translation, actually... they say the wheels and brakes will prevent you from crashing.... ummmm.... :-D

Thank you all for your responses! I will keep this advice in mind : )