I do both forward and reverse searches. I try to keep it to a minimum, but it's hard to avoid when trying to position a tape for an edit. On rare occasions the recorder will hesitate longer than normal when switching from search to play mode, but I avoid that by hitting stop first.
Even in search mode the speed of the tape is slow compared the speed of the heads, so I have a hard time seeing how head wear would be any different than normal. No doubt the tape tension and path over the cylinder shifts slightly during search (particularly in reverse), which might account for the slow pickup upon returning to play. Also, during search mode, the heads cross over tracks on the tape, so I guess it could be argued that the heads pick up debris between the tracks. That seems unlikely, however, because the heads are much wider than the tracks and always overlap during play and record modes.
My experience has been on machines with new heads. Worn heads become contaminated very easily, and what I said above may not apply in that case.
Analog -- Always out of adjustment.
Digital -- Always one more bug.