That is part of flipping. I like those who do it with a little grace like spending a few hours cleaning and fixing then making a nice listing like "Vintage Trek, just bought and spent a few hours fixing it up, works great now. $xxx obo. In my book, honesty is best policy and attracts buyers who may have seen the old ad but were afraid of buying because it needed work. They might not pay $250 but you could deal and still pull a profit and both buyer and seller are happy.
The new seller in this case sucks at selling and I hope his $100 is tied up for a long time