Yeah specualtive sacrifices on f2/f7 are bad. Only do it if you know it's good, so if you can see your way to regaining your material or getting an overwhelming attack. You'll often see computer engines apparently randomly sacrificing on f2/f7 as a way of handicapping themselves so they play at a lower level. Usually the defender can still castle easily by hand by just bringing the rook to the (now half-open) f file and tucking the king back. The only time I can think of this being playable is the cochrane gambit in the petroff but that's dubious at best even if you really know what you're doing, and even then it's probably not great if your opponents are prepared for you.
Bishop taking f2 pawn castle prevention
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I used to play against someone who would often throw a minor piece at the king side pawns to prevent castling. In most cases, it wasn't worth it for him. If you can immediately follow up with a strong attack, or if its part of a combination that recovers the material, ok go ahead. I just lost a game where my opponent made two minor piece sacrifices, but one regained the material and won a pawn in the process, and the other, a true sacrifice, left my king position so open I was unable to prevent mate. Just giving up a piece for a little king exposure in unsound, unless you already have pieces in that sector of the board that can press an immediate attack.
I would summerize a speculative attack on f2 black shooting himself in the foot to sharpen the position. There are very few lines where this is sound, honestly the only line I know of is in the italian two knights traxler variation. And for that to work, white has to waste tempo (Ng5, Nxf7). And even then the best it gets is a draw.
what does everyone think of taking a minor peice like the knight or bishop and attacking the f2 pawn which prevents the king from castling when he recaptures? I see it a lot in openings as a possiblity and it always makes me nervous when my only defense on the f2 pawn is the king precastling