The reasons why dogs like to dig into their crotches may be as follows:

Explore: Dogs may be interested in humans I feel curious about the smell on my body and want to explore it.

Playing: Some dogs regard getting into people’s crotches as a game, chasing, scratching and biting people’s legs endlessly.

Seeking attention: Dogs may attract the attention of their owners through the behavior of digging into their crotches, in order to gain more attention and companionship.

Lack of proper education: If a dog has not received proper behavioral training, it may not know that its behavior is inappropriate.

Anxiety: Some dogs may exhibit crotch-picking behavior due to anxiety or nervousness, possibly because they feel uneasy or insecure.