Often the full terms aren't even presented to until after you have paid money to reserve the apartment, and you have no real negotiating power. These are unconscionable contracts of adhesion.
1) "Unconscionability" is an extraordinarily high bar to meet. You should be very careful when you describe something as "unconscionable," because the odds are very good that the court is going to disagree with you.
2) They are not contracts of adhesion. First of all, even if the full terms are not presented until later (which is a change from every apartment I've ever rented--I have always had to sign both the lease agreement and the "community rules" documents), that doesn't necessarily mean that you're unable to reject them. As techies, we should probably be familiar with ProCD, Inc. v. Zeidenberg, 86 F.3d 1447 (7th Cir., 1996), as it is the case which most directly approved shrink-wrap licenses. The court in Zeidenberg said:
Transactions in which the exchange of money precedes the communication of detailed terms are common. Consider the purchase of insurance. The buyer goes to an agent, who explains the essentials (amount of coverage, number of years) and remits the premium to the home office, which sends back a policy. On the district judge's understanding, the terms of the policy are irrelevant because the insured paid before receiving them. Yet the device of payment, often with a “binder” (so that the insurance takes effect immediately even though the home office reserves the right to withdraw coverage later), in advance of the policy, serves buyers' interests by accelerating effectiveness and reducing transactions costs. Or consider the purchase of an airline ticket. The traveler calls the carrier or an agent, is quoted a price, reserves a seat, pays, and gets a ticket, in that order. The ticket contains elaborate terms, which the traveler can reject by canceling the reservation. To use the ticket is to accept the terms, even terms that in retrospect are disadvantageous. See Carnival Cruise Lines, Inc. v. Shute, 499 U.S. 585, 111 S.Ct. 1522, 113 L.Ed.2d 622 (1991); see also Vimar Seguros y Reaseguros, S.A. v. M/V Sky Reefer, 515 U.S. 528, 115 S.Ct. 2322, 132 L.Ed.2d 462 (1995) (bills of lading). Just so with a ticket to a concert. The back of the ticket states that the patron promises not to record the concert; to attend is to agree. A theater that detects a violation will confiscate the tape and escort the violator to the exit. One could arrange things so that every concertgoer signs this promise before forking over the money, but that cumbersome way of doing things not only would lengthen queues and raise prices but also would scotch the sale of tickets by phone or electronic data service.
In the event that you actually do find objectionable terms after signing (and why didn't you ask for a copy of the lease agreement to begin with?), you have the option of repudiating the agreement when you discover the objectionable terms. By continuing to move in and take advantage of the lease, you signal your acceptance of the apartment complex's offer. You don't get to take advantage of the offer, then complain later that you didn't like the terms.
And, for the record, the terms *can* be negotiated. I know because I've done it with nearly every apartment I've rented, having clauses struck that I didn't like and adding clauses I wanted. The idea that it's a contract of adhesion fails on several points, and "unconscionable" is laughable at best.