We are a 50/50 member guild, we lost our first TW but won our second TW. In the first one we had 41 members play and in the 2nd we had 37. Not intentional as the way i see it i would like all members to play which isn't always possible.
I wouldnt want our guild to win and then be accused of not fielding a full 50 team. We generally get between 35-45 members participate and raids and TB, we do try and remove and replace inactive members.
However i don't think its underhanded tactics and intentional for all guilds!