#1 and only factor to account for a drop off of YOUR sales during the summer is because affiliates tend to work less because: kids out of school and home all day, the affiliate goes on more vacations, the weather is nice so the affiliates spends more time outside, etc...
The affiliates works less during the summer and then wonder why their sales drop off some, then instead of blamming it on themselves for working less they blame it on the " summer slow down".
For Sponsors, same thing applies, their sales drop off because the majority of their affiliates work less and therefore make less signups. The sponsors blame it instead on the " summer slowdown " and the affiliates buy into this myth and take the attitude, well its the summer and it is slow so i am going to work less
There is NO big drop off of customers, just like during christmas, during tax season, when the kids go back to school, or the kids are out of school, during football season, when the economy is bad, gas prices are up, the weather is bad or good, it does not matter there is always shit going on out there and there is always lots of customers to sell to.
People looking for " slow downs " are people looking for excuses of why they are not making more money. A "slow down" could be found every day of the year for one reason or another.