see if you can convince me even on these, or if I was right to remove them because they are weak
As said above, I think "removing because weak" is not really right, because it doesn't help you much. Only a tiniest fraction of strategies really use all 10 cards, so it does not really influence much if there is 1 more weak card on the board, because you wouldn't buy a strong one either as it doesn't fit your strat.
now I want to say please, what do you think of:
Instead of this, I will just say in which situations the card is helpful, so you can decide for yourself.
wishing wells
Is nice if you can pick them up easily (Workshops/Ironworks), and/or if one particular card dominiates your deck (maybe Conspirator). Said that, of course also a possible activator for it. Usually not game changing.
saboteur
Is weak but can lead to group-think it is strong, which is even worse. Everybody destroys everyones deck, you have to like it to find that funny. Usually only strong if you have a deck to play it every turn, and then most of the time you either have a better payload and/or add insult to injury for your opponent. Probably one of the cards that is really banned from some tables with informed players.
scouts
Would probably be voted worst card of the game if you ask here. Interactions where already mentioned, with only 3 sets it's still stronger than in full random, but you probably won't miss it.
chancellor
Game-accelerator when you don't have other terminals (or plan on getting enough Villages) or want to get to some key-card fastly (Mountebank, Goons). Not game-changing. Strong combo with Stash, but that's about it.
loan
Trashing is strong, especially in Colony games. Not being able to trash Estates is a drawback, but maybe something else can do this (Remodel), but can't trash Coppers (well). Loan trashes without the need of an action, so you can safely open with a terminal. If you want to go for an engine (maybe you tasted some blood once you played more with Chapel), getting rid of 7 Coppers really helps colliding thing, but build-up is more difficult because of the left Estates.
trade route
Did I say trashing is good? This one is also quite weak, especially as long as it gives +$0. May assist Loan by trashing the Estates. Quite strong against Cursers as you have much to trash there and usually Duchies are touched quite early there, getting Trade Route to $3 quite early in the game. Also possibly strong with or against alternative Victory points, or other cards that give you/your opponent(s) incentives to buy/gain Victory cards early in the game (Hoard).
counting house
Needs all-in on the strategy, and is still mediocre in that case. Best is defend against Mountebank. Otherwise, on weak boards possible to grind your VPs with it. Probably nothing (except counter Mountebank) which I would advice to do until you have played some more games.
contraband
Good if you have alternatives to buy. So either you want 2 small engine pieces over Gold (or could at least live with it), or there are alternatives at the $6 price point (Hoard, Harem, Nobles, Goons), so your opponent has a hard time guessing what you want (or you wouldn't mind either way). Remember, you don't have to play all your money at once, so first playing the Contraband before playing the rest of your money doesn't give you opponent to much information on what you can afford.