Networking mongrels are those people who have used and abused networking:

They collect a meaningless stack of business cards without ever connecting with the people.
They try to make the "sale" at a wedding, networking event or first
encounter.
They talk and focus on their agenda rather than listening with interest to gather information.
They intrude inappropriately and have short, superficial interactions.
They walk over people and forget the value of taking the time to establish relationship and rapport.
They get caught up in quantity rather than quality.

If you have had an unpleasant or uncomfortable networking experience, it is probably due to the abuse or misuse of the concept by a networking mongrel.

Don't be a networking mongrel or you will turn people off and miss the
magnificent opportunity of powerful networking.

(adapted from The Power of Networking by Sandy Vilas & Donna Fisher)