Revealing cards until you reveal a card which meets certain criteria "usually" has the consequence of leaving you, on average, with a lower proportion of cards in your deck which meet that criteria.
So, on average, loan leaves you with a deck with proportionally less treasures, and saboteur leaves you with a deck with proportionally less cards costing 3$+. The effect, however, is pretty ignorable, on average.
This can be demonstrated (painfully), but if you want to visualize it, imagine the extreme case of two players that open saboteur/nothing, and assume that P1 plays saboteur turn 1, before P2 has a chance to draw his five cards because of some obscure rule that doesn't exist. So P2 is left with 0/n cards costing 3$+ in his deck (n being the number of cards not cycled, and averages 5), which is lower than the normal 1/11.
Actually, if you do this calculation, what you find is that this extreme case (with only 1 saboteurable card in the deck) is a singular one. For any other number of saboteurable cards in the deck the remaining deck quality does not change.
EDIT: to clarify, this has nothing to do with reshuffle. If you know you have exactly 1 saboteurable card in your remaining deck, then you know you will not trigger a reshuffle by the saboteur. As long as that card is not the last card in your deck, your average quality of the remaining deck will be 0. If that card is the last card, the remaining deck quality is undefined; but any sensible definition will not define that to be higher than the original average, so in this case the average quality of the next card is indeed lower.
It is quite curious why this case is just different from the cases for all other number of saboteurable cards in your deck though.
I think it is a mistake even to think about the value of an empty draw deck.
Suppose the draw deck contains at least one card worth $3 or more, and Saboteur is played.
1. Saboteur does not worsen the expected value of the next card drawn provided the reshuffle is not triggered by drawing that card.
2. Saboteur may worsen the expected value of the next card drawn if the reshuffle is triggered by drawing that card (this depends on the contents of the discard pile)
3. Saboteur hastens the reshuffle.
In the case of exactly one card in the draw deck costing $3 or more and none in the discard, points 2. and 3. conspire to make the expected value of the next card worse.